"We will deliver this urgent call from the national conference to Moqtada al-Sadr ... to try to solve this problem at its roots," Sadr, a distant relative but a political opponent of the cleric, said on the sidelines of the three-day meeting.

The delegation would try to give Sadr a letter, urging him to leave the Imam Ali shrine and turn his Mehdi Army into a political party, delegates said.

But the cleric has shown little sign of compromise, vowing to fight to the death if necessary.

He has demanded U.S. forces leave Najaf and the government grant an amnesty to his fighters as part of any deal to end the 12-day conflict across eight cities.

Three U.S. soldiers were killed in action on Sunday in Najaf province, the military said in a statement. It gave no details.

A French journalist holding a U.S. passport has been seized in the southern city of Nassiriya, Al Jazeera television reported. The television said it had "learned" the journalist was an archaeological reporter.

The Interior Ministry said it was checking reports that journalist Micah Jaren and his Iraqi translator were missing in Nassiriya.

The French and American embassies said they had no information on the report. Last week, gunmen kidnapped and then freed a British journalist in the southern city of Basra.

Militants in Iraq have waged a campaign of kidnapping aimed at driving out individuals, companies and troops supporting U.S. forces and the new Iraqi interim administration.

DEEP DIVISIONS

Despite the apparent pro-government stance of the delegation, the conference has exposed deep divisions in Iraq over Najaf, with many delegates upset that U.S. forces are fighting so close to Shi'ite Islam's holiest site.

Some have threatened to quit an event already beset by boycotts from players such as Sadr and other religious groups.

"I can tell you that the Najaf fighting is dominating the whole conference," said Hamid al-Kifaey, one delegate.

Insurgents fired mortars at the meeting just hours after it opened on Sunday, killing at least two people on the edge of the fortified compound where the gathering is being held.

The brazen attack starkly illustrated Iraq's precarious security as politicians and religious leaders plot the country's road to democracy ahead of landmark elections in January.

The meeting will choose a 100-member assembly, or national council, to oversee Allawi's interim government until elections in January.

Fighting between U.S. forces and Sadr's militia also broke out in a Shi'ite slum in Baghdad, witnesses said. They said U.S. troops were sealing off the area, called Sadr City.

While clashes have resumed in Najaf since the collapse of peace talks on Saturday, U.S. and Iraqi forces have not launched a fresh all-out offensive.

Thousands of protesters from southern Iraq have joined Sadr in the mosque, promising to act as human shields.

Iraq's Interior Ministry said it had issued an order for Iraqi and U.S. forces not to attack the shrine. Such an assault would trigger outrage among Iraq's Shi'ite majority.

Once appointed, the assembly will be able to veto legislation with a two-thirds majority, approve Iraq's 2005 budget, and appoint a new prime minister or president should either resign or die in office.

The Shi'ite uprising forced Iraq to keep a main southern oil pipeline shut on Monday, reducing export flows by almost half, a South Oil Company official said.

The Mehdi Army has threatened to attack oil infrastructure, helping drive oil prices to record highs.

(Additional reporting by Micheal Georgy in Najaf, Omar Anwar, Matthew Green, Waleed Ibrahim and Khaled Yacoub Oweis in Baghdad)

By ABDUL HUSSEIN AL-OBEIDI, Associated Press Writer

NAJAF, Iraq - U.S. tanks rolled into the Old City of Najaf toward a holy Shiite shrine where militants were hiding Monday as participants at a national conference voted to send a delegation here to try to negotiate an end to the fighting.

Slideshow: Iraq

The city, which had been quiet early Monday, was hit by series of explosions in the late morning that shook the vast cemetery, the scene of many battles between U.S. forces and militants. Witnesses also reported U.S. tanks had moved to within 500 yards of the revered Imam Ali Shrine.

"We are proceeding with our operations. We are moving forward and we captured some positions inside the Old City from the south during the night and this morning," Police Chief Brig. Ghalib al-Jazaari said.

Fighting resumed Sunday after negotiations and a cease-fire collapsed. Two U.S. soldiers were killed in Najaf fighting Sunday, and a Marine was killed in Iraq's western, largely Sunni province of Anbar. At least 934 U.S. servicemembers have been killed in Iraq since March 2003.

Also Monday, officials reported that a French-American journalist and his Iraqi translator have disappeared in the southern city of Nasiriyah.

The journalist, Micah Garen, and his translator Amir Doushi went missing while walking through a busy market in the city, said Adnan al-Shoraify, deputy governor of Dhi Qar province. He said the translator's family had first reported the two missing.

The Arab television station Al-Jazeera said the journalist had been kidnapped and provided no other details. Al-Shoraify could not confirm whether Garen, 33, was abducted.

The fighting in Najaf has cast a pall over the National Conference in Baghdad, an unprecedented gathering of 1,300 religious, tribal and political leaders from across Iraq meant to be a key first step toward democracy.

Some of the delegates threatened to walk out unless the crisis was resolved. On Monday, the conference voted to send a delegation to Najaf to ask radical Shiite cleric Muqtada al-Sadr to tell his followers to drop their weapons and join the country's political process.

"The door is very open to all Iraqis, regardless of their religion, ethnic background, to join the free political process," Shiite cleric Hussein al-Sadr, a distant relative of Muqtada al-Sadr, told the conference.

Muqtada al-Sadr's aides said they supported efforts to end the violence.

"We are ready to accept any mediation for a peaceful solution," al-Sadr aide Ahmed al-Shaibany said.

At the same time, however, al-Shaibany called on tribal chiefs throughout Iraq to travel to Najaf to form human shields to protect al-Sadr's Mahdi Army militant and the Imam Ali Shrine.

Fighting on Sunday apparently caused minor damage to the outer wall of the shrine compound, ripping off some tiles and leaving some holes.

With Sunday's deaths, at least eight U.S. troops have been killed in Najaf, along with about 20 Iraqi officers, since fighting there began Aug. 5. The U.S. military estimates hundreds of insurgents have been killed, but the militants dispute the figure.

In other violence, two civilians were killed and four others injured in the city of Baqouba on Monday when a mortar hit their house, said Ali Hussein, a medic at the main hospital in Baqouba.

It was not known who fired the mortar, but insurgents frequently clash with U.S. troops and Iraqi security forces in the city, 35 miles northeast of Baghdad.

A roadside bomb in Baqouba also wounded three members of the Iraqi National Guard, said Zuhair Abdul-Kareem, one of the injured guardsmen.

In the volatile Sunni city of Fallujah, west of Baghdad, U.S. warplanes bombed three neighborhoods Sunday afternoon, killing five civilians and wounding six others, said, Dr. Adil Khamis, of Fallujah General Hospital.

The three-day conference, which started Sunday, aims to give a broad spectrum of Iraqis a voice in the political process and increase the legitimacy of interim Prime Minister Ayad Allawi's interim government, which is deeply dependent on American troops and money even after the end of the U.S. occupation.

Just hours after the heavily guarded meeting began, however, insurgents fired a mortar barrage that landed at a nearby commuter bus station, killing two people and wounding 17 others, according to the Health Ministry.

The mortars apparently were aimed at the fortified Green Zone enclave where the conference was taking place, police said.

The continued Najaf fighting has undermined Allawi's attempts to show he is in control. The country's Shiite majority has been angered by the sight of U.S. troops firing around some of their holiest sites — and many have blamed the Iraqi government.

Some conference delegates have staged loud protests and others have threatened to pull out if the violence does not end.

In an attempt to assuage the complaints, a working committee was formed to find a peaceful solution to the tension in Najaf.

Cabinet minister Waeil Abdel-Latif warned of a new major offensive in Najaf unless the militants drop their weapons, get out of the city and transform themselves into a political party.

"We shall give the peaceful way a chance ... and after that, we shall take another position," he said Sunday.

He also said foreign fighters were among the militants captured in Najaf — a repeated government claim — and he played a video that showed interviews with Iranian, Egyptian and Jordanian fighters and boxes of weapons, reportedly from Iran.

Al-Sadr, a fiery young cleric, has drawn support among some with his denunciations of the continued U.S. domination of the country. He has depicted the fight by his followers as a campaign against occupation.

BAGHDAD, Aug. 15 -- More than 1,100 Iraqis convened Sunday for the start of a conference aimed at selecting a national assembly, a milestone in the country's transition to democracy, but the high-security meeting was roiled by a dispute over the use of military force to confront militiamen loyal to a rebellious Shiite Muslim cleric.

In a remarkable scene of political activism that would have been unimaginable under Baath Party rule, dozens of Shiite delegates jumped to their feet in a loud protest of the interim government's decision to mount military operations to evict followers of the cleric, Moqtada Sadr, from a Shiite shrine in the holy city of Najaf. Chanting "Yes to Najaf!" and raising their fists, the Shiite dissenters demanded that the participants call on the interim prime minister and Sadr's followers to refrain from violence and for a special committee of delegates to negotiate a solution to the crisis.

The outburst triggered a succession of events that quickly reshaped government policy toward Najaf and instilled the first measure of checks-and-balances in Iraq 's nascent political system. The Shiite protesters, along with several non-Shiite participants, caucused and drafted a letter to interim Prime Minister Ayad Allawi and his cabinet that called for a dialogue with Sadr and "an immediate cease-fire and cessation of all military activities in Najaf and other Iraqi cities."

A four-person delegation from the conference then met with Allawi. When the meeting was over, the government announced that its plans to use force to expel Sadr from the Imam Ali shrine were on hold. In a reversal from its position a day earlier, Allawi's cabinet issued a statement pledging to refrain from military action against Sadr's militiamen and to keep an "open door" to a negotiated settlement.

"This is democracy in action," said Ibrahim Nawar, a U.N. adviser who helped organize the conference. "For now, at least, they have succeeded in changing the government's approach toward the situation in Najaf."

Although senior officials said units from the Iraqi army would still be deployed to Najaf to prepare for an assault on the shrine should Sadr not withdraw, they acknowledged their strategy had shifted. "We're going to give time for a peaceful solution," said Wael Abdul-Latif, the minister of state for provincial affairs.

Shortly after the Shiite protest, a half-dozen mortar rounds landed near the heavily fortified conference center, killing two people and wounding 17 others at a nearby transportation depot, where three buses were reduced to charred hulks. The meeting was not interrupted, but the attack pierced an extraordinary security umbrella that involved curfews in nearby neighborhoods and numerous vehicle checkpoints.

The Shiite protest over Najaf provided a window into the chaotic fervor with which Iraqis are embracing democracy. Through their demands of Allawi, the delegates started to create a balance of power in the political system, even before winnowing themselves into a 100-member national assembly. But the protest also revealed the degree of Sadr's influence and the extent to which Iraqi society remains riven by differences that could impede its democratic transition.

Speaker after speaker rose to condemn the use of force against Sadr and his militiamen. "What is happening in Najaf is much more important than this conference and demands our immediate attention," one man intoned. Another likened the tactics used by U.S. and Iraqi security forces to those employed by the military under Saddam Hussein's government to crush Shiite dissent. A woman rose to criticize Sadr, saying "it is not American cannons" that are responsible for the bloodshed there, but was shouted down.

Members of the interim government have maintained that few Iraqis endorse Sadr's lawlessness and that many back Allawi's tough tactics to restore order in this strife-torn country. But the delegates, who are supposed to represent Iraq's 25 million people, took a more nuanced approach to the standoff in Najaf, where scores of fighters from Sadr's Mahdi Army militia have been holed up in the Imam Ali shrine. Despite strong support for aggressive action to combat criminals and insurgents, many of the conference participants -- not just Shiites, but rival Sunnis as well -- rejected the idea of using force to liberate the shrine and apprehend Sadr, who is a descendant of the prophet Muhammad.

"We want the immediate stoppage of bloodshed in Najaf," said Hussein Mohammed Hadi Sadr, a Shiite cleric who is a distant relative of Moqtada Sadr and served as the conference's chief emissary to the prime minister. "It is a holy place. We should not fight there. The language of dialogue should be the overruling language."

Others were more blunt. "How can we have a conference if we have a war in Najaf?" growled Nadim Jabbari, the leader of a small Shiite party in Baghdad. "We must solve that problem first."

Solving that problem delayed other business at the conference. The delegates are supposed to select a 100-member interim national assembly by Tuesday. By the end of the day Sunday, they had not even agreed on the rules by which members would be elected. The organizers want delegates to vote on slates of 81 candidates -- 19 members of the former U.S.-appointed Governing Council have been guaranteed seats -- but some participants, particularly those who are political independents, say they believe that method favors political parties and instead want assembly members to be elected individually.

The assembly, which will have the authority to veto decisions issued by Allawi's cabinet, will be replaced after national elections are held. Those elections are scheduled for January.

The conference had been postponed for two weeks to attract more participants. It was supposed to be limited to 1,000 members, but political advisers from the United Nations asked organizers to invite 300 additional people, many of them from religious and ethnic groups that were deemed underrepresented. More than 1,100 of the 1,300 attended on Sunday, said Fouad Masoum, the conference chairman.

"Your blessed gathering here is a challenge to the forces of evil and tyranny that want to destroy this country," Allawi told participants in an opening address. He called the gathering a "first step that will open up horizons of dialogue" and serve as "an example for democracy and freedom" in the Middle East.

But it was Allawi's vow last week that he would not negotiate with Sadr that resonated even more profoundly at the conference. Abdul-Latif, the minister of state for provincial affairs, said that the government had repeatedly asked Sadr to withdraw his militia from the shrine. Abdul-Latif also noted that Allawi's national security adviser recently traveled to Najaf to negotiate, but Sadr would not meet with him.

Abdul-Latif said the government would give Sadr "reasonable time" but not an indefinite period. If the militiamen do not vacate soon, he said, "we will pursue them."

Conference organizers said a group of delegates would travel to Najaf, perhaps as early as Monday, to try to persuade Sadr and his militia to withdraw from the shrine and lay down their weapons.

In his opening address, President Ghazi Yawar urged the delegates to "achieve national consensus and agreement."

Ashraf Jehangir Qazi, a former Pakistani ambassador to Washington who is serving as U.N. Secretary General Kofi Annan's special representative in Iraq, told delegates that the gathering was "a critical milestone on the path toward a goal shared by all Iraqis -- the goal of seeing their beloved country become a stable, pluralistic and inclusive democracy." He insisted that strife could not be addressed "through security measures alone. They require political consensus-building, rehabilitation measures and the promotion of the rule of law."