Two terrorists shot their way into a Palestine Liberation Organization office yesterday and machine-gunned four people to death in the bloodiest attack yet in a worldwide vendetta between the PLO and pro-Iraqi radicals.

The gunmen killed a Pakistani policeman and three Palestinians - the mission's telex operator, a medical student and a guerrilla studying with the Pakistan Army - and escaped.

But the Islamabad gunmen missed their primary target, PLO chief of mission Yousuf Abu Hantash, who hid in his office while his would-be assassins ran through the halls shouting for him.

"This was a serious action plotted by the Iraqi government," Hantash said. "The Iraqi Embassy supplied them with machine guns and organized the attack. We hold the Iraqi government responsible."

In Beirut, the PLO also accused the Iraqi government of planning the assault and said police in Bangladesh had intercepted a load of weapons intended for another attack on PLO headquarters in Dacca.

Palestinian officials have warned that the Arab vandetta threatens to start a full-scale "civil war" among Palestinians scattered around the world.

In the attack in Islamabad, the Pakistani capital city, police guards stopped the two gunmen at the PLO mission gate and asked to search a bag containing their machine guns and hand grenades.

As they argued, the Palestinian Telex operator. Saad Abu Nassar, came out of his office. One of the attackers grabbed him and the other shot him and a policeman, leaving the area splattered with blood.

The two then burst into the building shouting for Hantash.

"They were shouting for me. I was sitting in my office but they didn't enter it," the PLO chief said.

Instead they found Omar Khan Far, a Palestinian studying medicine in Pakistan. They shot him down without seying a word. Their fourth victim was the Palestinian guerrilla, Mohammad Hussain.

The two then rushed out the doorway, hurling at least two hand grenades as they escaped.

The Islamabad incident was the sixth in a series of attacks in London, Kuwait. Paris and Karachi spawned by the feud in the Palestinian high command. With four fatalities, it was the bloodiest so far.

Two PLO officials in Paris were killed Thursday by pro-Iraqi gunmen and about 2,000 chanting, shouting Palestinians gathered in a mosque in the Left Bank's Latin Quarter yesterday to mourn them.

"With our souls and with our blood we shall avenge you," chanted PLO supporters at the funeral for the PLO's chief representative in France. Ezzedine Kalak, and his deputy. Adnan Hammad, who were killed when the two gunmen burst into their office firing submachine guns and throwing grenades.

The top surviving PLO official still in Paris accused Iraq of being behind the killings.

In Beirut, the PLO yesterday angrily denounced Iraq for sending agents to attack PLO offices around the world but said it would not retaliate.

Two gunmen detained in Paris were charged yesterday in the attack with premeditated murder, which carries a possible death sentence. They were identified as Hatem Abdul Kadir, 25, and Kayed Hassad, 21, both Jordanian nationals but believed to be of Palestinian origin.

Ambassadors of Arab countries attended the funeral service at the mosque in the Latin Quarter.

But the new Iraqi ambassador, who arrived Friday in Paris was absent. He declined to speak to reporters on his arrival even though Iraq has denied any involvement in the killings.

On Wednesday, two Arab gunmen reportedly PLO Al Fatah commandos, raided the Iraqi consulate in Karachi. One of the gunmen was killed and the other died yesterday in a hospital.

The vendetta stems from a bitter personal rivalry between PLO chief Yasser Arafat and a man known by the code name of Abu Nidal, who broke away from Arafat and established his own, more radical group in Baghdad.

In Beirut yesterday, five radical Palestinian groups called for an end to the clashes and said all differences should be resolved through "democratic dialogue and not armed confrontation."

The call came after repeated clashes between the radicals and Arafat's Fatah group in Palestinian refugee camps in Lebanon, leaving dozens of casualties, mainly on the radical side.