The Palestinian Authority has called for an emergency UN Security Council to condemn Israel's deadly offensive. President Yasser Arafat described the killings as an "assassination and dirty operation" warning Israel will pay the price.

Report: Israel unleashed a fierce naval and helicopter onslaught near the Khan Younes and Jabalya refugee camps in Gaza, injuring 15 Palestinians. Israeli helicopters attacked a security compound 300 meters from Palestinian President Yasser Arafat's headquarters, destroying some eight armored personnel carriers.

Israeli troops also shot dead five Palestinian policemen near the West Bank town of Beituna, after a brief invasion of the autonomous area. Israeli soldiers demolished a police station and a private residence.

The bodies of the policemen were riddled with machine-gun fire and dumped near Ramallah. The Israeli army claimed it opened fire on the policemen after soldiers saw what it described as "suspicious figures" somewhere they are not supposed to be in.

The Palestinian Authority appealed for an emergency meeting of the UN Security Council. Top officials also slammed Washington for blocking the dispatch of an international peacekeeping force to protect civilians in the occupied territories.

In Tel Aviv, a bomb was defused Monday. It was hidden in a plastic bag.

Tensions are expected to rise before Tuesday's anniversary of the 1948 "Nakba" or "Great Catastrophe", when Israel expelled hundreds of thousands of Palestinians from their homes following its creation. In a move that will further heighten tensions, Israel vowed to formally reject criticism by a US-led commission investigating the Palestinian uprising...

AIN EL-HILWEH, Lebanon 15 (Reuters) - Thousands of Palestinians demonstrated in refugee camps in Lebanon on Tuesday to mark the Nakba, or Great Catastrophe, of Israel's birth and vowed to continue fighting the Jewish state.

"Let us throw away the olive branch and carry our rifles to return to our land," shouted black-clad protesters who marched through the Ain El-Hilweh refugee camp near the southern port city of Sidon.

Thousands of men, women and children looked on while demonstrators burned American and Israeli flags. Schools and shops closed to mark the day.

Palestinians annually commemorate the Nakba, when 700,000 Palestinian refugees were forced to flee their homes in the fighting that accompanied the creation of Israel in 1948.

Palestinians also protested in front of the headquarters of the U.N. Interim Force In Lebanon (UNIFIL) in Tyre and urged international institutions to intervene to protect Palestinians in the West Bank and Gaza Strip.

"We want (Israeli Prime Minister Ariel) Sharon to be tried as a war criminal," refugees said in a petition delivered to the the U.N.Similar demonstrations also took place in other refugee camps in the country.

Ain El-Hilweh is Lebanon's largest Palestinian refugee camp. Lebanon has about 360,000 registered Palestinian refugees.

GAZA, May 15 (Reuters) - Israeli forces killed a bodyguard of the founder of the Islamic guerrilla group Hamas on Tuesday and wounded six other people, Palestinian police and Hamas officials said.

Hamas officials said the killing was an assassination and vowed revenge.

The latest violence came as Palestinians marked their Nakba, or Great Catastrophe, a day mourning their exile after Israel was created in 1948.

The Israeli army said a tank shell struck two Palestinians who had exited a car and launched a mortar bomb near the Nahal Oz checkpoint on the Gaza-Israel border.

"These two Palestinians were hit and killed and the army confiscated the mortar launcher," an army spokesman said.

Palestinian police said only one man had been killed. They said Israeli tanks at Nahal Oz fired three shells and opened heavy fire at a Palestinian police post on the Gaza side, also hitting a car in which the man was killed. Six other people in the area were wounded, the police said.

Palestinian witnesses said an Israeli tank pushed the car into Israeli territory after the incident.

Hamas officials said the Palestinians involved were members of their movement. They identified the man killed as Abdel Hakim Al-Manaema, a bodyguard to Hamas founder Shiekh Ahmed Yassin.

Senior Hamas leader Abdel-Aziz al-Rantissi accused Israel of a "sinful assassination operation to be added to the long files of Israel's crimes."

Hamas officials gave a different account of the attack, however, saying that an Israeli helicopter gunship had fired missiles at the men. The army denied it carried out a missile strike.

"Hamas will never keep silent and it will chase this enemy in every place and will get the revenge for the martyr soon," Rantissi told Reuters.

Hamas has opposed interim peace deals signed between Israel and the Palestinians and has taken an active role in the current uprising.

Palestinians called for peaceful marches across the West Bank and Gaza on Tuesday to mark the Nakba, or Great Catastrophe, when 700,000 Palestinians became refugees in the Arab-Israeli war that followed Israel's birth in 1948.

RAMALLAH, West Bank, May 15 (Reuters) - Palestinians observed three minutes of silence on Tuesday as sirens wailed across the West Bank and Gaza Strip to mark the 53rd anniversary of what Palestinians call their Nakba, or Great Catastrophe.

As the clock struck noon in the West Bank and Gaza Strip, Palestinians stood still in the streets and shops to mark the mass displacement of people from towns and villages in British-mandate Palestine that became part of Israel in the 1948 Arab-Israeli war.

After the sirens died down, the Palestinian national anthem blared and people held up their fingers in a V-sign, symbolising victory in the revolt against Israeli occupation that has raged for almost eight months.

Muslim preachers shouted Allahu Akbar (God is greatest) through loudspeakers from mosques and church bells rang.

Palestinian media broadcast a pre-recorded speech by Palestinian President Yasser Arafat over radio and television.

More than 15,000 people crowded Gaza City's Palestine Square to hear Arafat, whose address was followed by a speech from Palestinian poet Mahmoud Darwish. Some wore black as a sign of mourning, others draped black cloth over small Palestinian flags.

"Our response to the Nakba should be to establish our state and achieving the return (of refugees)," read banners in the square.

This year's anniversary falls against the backdrop of violence in which at least 421 Palestinians, 79 Israelis and 13 Israeli Arabs have been killed since the revolt for independence erupted last September.

Waving Palestinian flags, many of the three million Palestinians in the West Bank and Gaza Strip took to the streets in protests against Israel.

In the West Bank city of Nablus, around 40 children carried the names of their cities and villages to commemorate the loss of their homeland.

The number of Palestinian refugees has swelled since 1948 to about four million people in camps in the West Bank, Gaza and neighbouring Arab states, where demonstrations were also planned.

RAMALLAH, West Bank (AP - 15 May) - Tens of thousands of Palestinians jammed streets and town squares in the West Bank and Gaza Strip on Tuesday, standing in silence during a three-minute siren to mark ``Al Naqba,'' or the catastrophe, as they call their displacement during Israel's founding in 1948.

Palestinian leader Yasser Arafat, referring to eight months of fighting with Israel, said his people would not surrender. ``Faith, faith, courage, courage, stand strong in the face of this increasing aggression, for the sake of freedom,'' Arafat said in the taped speech broadcast to the crowds over loudspeakers.

Arafat had left for Cairo earlier Tuesday, drawing Israeli criticism that he had slipped away to avoid being blamed for possible violence on Al Naqba day. Israel commemorates the day of its founding - May 15, 1948 - according to the Hebrew calendar, which this year put it on April 26.

After the ceremonies, several hundred Palestinians threw stones at Israeli troops in several locations. About two dozen Palestinians were wounded by live fire and several more by rubber-coated steel bullets.

In the Gaza Strip, a bodyguard for the founder of the Islamic militant group Hamas was killed by Israeli tank fire after shooting a mortar round at Israeli targets, the army and Palestinian officials said. A second bodyguard for Sheik Ahmed Yassin was critically wounded.

Hamas swore to avenge the death of Abdel Karim Maname, a longtime Hamas activist. ``Our reaction will be like an earthquake that will rock the ground under the feet of the Zionists,'' said Abdel Aziz Rantisi, a Hamas spokesman. The group has carried out a number of recent suicide bombings in Israel.

In last year's Al Naqba commemorations, four Palestinians were killed and at least 320 Palestinians and 15 Israeli soldiers were hurt.

Israeli troops tightened security ahead of Al Naqba, which comes on eight months of violence that have killed 449 people on the Palestinian side and 77 on the Israeli side.

At noon, a three-minute siren rang out, accompanied by the sounds of Muslim prayer calls and church bells. Marchers stood silently and motorists got out of their cars. Some Palestinians flashed victory signs and others pressed their right hand to their heart.

>From the Nusseirat, Bureij and Mughazi refugee camps in the center of the Gaza Strip, some 30,000 people walked to the main north-south road. The crowd chanted ``no surrender'' and ``The uprising will continue until we uproot the occupiers from our land.''

Several old men carried keys to their former homes in what is now Israel, and gunmen fired in the air.

Amina Abu Sadda, 55, wearing a traditional black robe with red embroidery, said she was 2 years old when she was displaced. ``I have fed my children, mixed in with the mother's milk, the words `right of return,''' she said as she walked in the march.

Some 30,000 Palestinians jammed the main square of the West Bank town of Nablus. The governor of the city, Arafat confidant Mahmoud Aloul, told the crowd that the struggle against Israel must continue. ``We must fight the killers of our children,'' said Aloul, whose son, Jihad, was killed by Israeli fire last fall.

In his taped speech, Arafat lashed out at Israel, though he never directly referred to the Jewish state. Arafat said that while Palestinians remained committed to peace, ``executioners continue to walk through the puddles of our blood with their military escalation and siege of our towns.''

He complained that the world has stood by silently while the Palestinians suffered. He said the Palestinians would only accept a peace deal based on a complete Israeli withdrawal from lands occupied in the 1967 Mideast war, and recognition of the right of Palestinian refugees to return to former homes in what is now Israel.

During the 1948 Mideast war that followed Israel's creation, an estimated 750,000 Palestinians, according to U.N. figures, fled or were driven out of their homes by Israeli troops. Many refugees and their descendants live to this day in camps in the West Bank, Gaza and neighboring Arab states.

Israel maintains that allowing the refugees to return would undermine the Jewish character of their state, where about 5 million Jews live. Israel agreed to allow some thousands of refugees return in the framework of family reunification, but said the rest must be resettled in the West Bank and Gaza or countries where they now live. The Palestinians rejected that proposal.