"We call on the international community to stop this bloodshed, this killing in cold blood, this state terrorism. We don't hear the U.S. administration or any other state speaking out about the killing of Palestinian children," said Saeb Erakat, the Palestinian senior negotiator.

The Palestinian leadership issued a statement calling on the United Nations to step in.

"We call on the U.N. Security Council to take up its responsibilities in the face of the war of extermination being waged by the government of (Israeli Prime Minister Ariel) Sharon against Palestinian civilians," it said.

"We are ready for a cooling-down period, but they (the UN) have left the Palestinian people at the mercy of force and Sharon's government."

Previous moves to sanction Israel in the Security Council have run into opposition from the United States, which as Israel's main ally and a permanent member of the council has blocked punitive measures against Israel demanded by Arab nations.

Nabil Abu Rudeina, top advisor to Palestinian President Yasser Arafat, called on the Middle East Quartet, made up of the United States, the United Nations, the European Union and Russia, to break off contact with Israel.

"This is the third crime in 48 hours, and a dangerous escalation," he said.

And information minister Yasser Abed Rabbo called for "an end to political and security contacts with Israel, as these contacts act as a screen for Israel's continuing assassination policy."

He did not say whether a decision had been made to break off such contacts, which have recently focused on a gradual Israeli withdrawal from reoccupied areas if the Palestinian police ensure an end to attacks against Israeli targets.

Erakat said the killing of four Palestinians near a Jewish settlement early Sunday, together with a rash of other attacks including the slaying of four Palestinian civilians last week in the Gaza Strip, was aimed at cowing the Palestinians.

"This escalation is designed to scare the Palestinian people and make them surrender. This is state terrorism," he said.

"The president of the United States said he'll fight terrorism, but Washington should know they are helping the biggest act of terrorism in the world, the Israeli occupation."

U.S. President George W. Bush has previously said that “Israel has the right to defend itself”.

Israeli forces killed four Palestinians near a Jewish settlement in Hebron on Sunday, with the army calling the slain men militants armed with sabotage equipment.