Jerusalem ? Israel began pulling forces out of the West Bank cities of Nablus and Ramallah on Saturday night, and officials said they would cooperate with a United Nations probe into the army’s devastating attack on the Jenin refugee camp.

The Israeli moves, however, did not include ending the siege of Palestinian Authority President Yasser Arafat’s compound in Ramallah. They came as President Bush was meeting at Camp David with members of his national security team, including Secretary of State Colin Powell, to discuss what peace efforts the United States might make next.

Powell, who on Wednesday ended a 10-day overseas trip focused on the Mideast conflict, failed either to persuade Israel to immediately withdraw from all Palestinian-controlled areas or to induce Arafat to declare a cease-fire.

U.S. Middle East envoy William Burns toured the wrecked Jenin camp Saturday as refugees and aid workers continued to search for bodies in the rubble. He declared it the site of “terrible human tragedy.”

But Israeli officials said they were confident the United Nations would determine that no massacre of civilians took place during the eight-day military offensive, as Palestinians have charged. Hospital officials in Jenin reported Saturday that 42 bodies had been pulled from the remains of homes and other buildings bulldozed during the furious Israeli assault. Twenty-three Israeli soldiers also were killed during the fighting in the camp, which Israel said it conquered because nearly two dozen suicide bombers came from its warren of homes.

Rescue efforts continued to be hampered by the presence of explosives left behind during the battle. A Palestinian medic who had volunteered his services suffered severe injuries to a foot Saturday when he stepped on what local doctors said was a mine. It was unclear whether the device was left behind by Israeli or Palestinian fighters.

“He was injured in the camp while helping pull people” from the rubble, said Dr. Mohammed Abu Gali, the director of Jenin’s main hospital.

Abu Gali said another man was lightly injured Saturday when part of his home collapsed, trapping him inside. He was freed by rescuers seven hours later.

Israel withdrew troops and tanks from Jenin and its refugee camp Friday and appeared set to make good on Prime Minister Ariel Sharon’s promise to President Bush that it would also be out of Nablus and parts of Ramallah by this morning. When the current intifada began more than a year and a half ago, Ramallah had long been the commercial and political center of Palestinian society. Nablus is the largest city in the West Bank.

But the pullouts are limited, designed to leave large forces poised to re-enter urban centers with ease.

Tensions continue to run high in both the West Bank and the Gaza Strip in the wake of Powell’s inconclusive visit.

The Israeli army reported that a suspected Palestinian suicide bomber exploded at a checkpoint on the western side of the West Bank town of Kalkilya Saturday afternoon, after soldiers there called on him to halt as he walked through. There was no immediate claim of responsibility by any group.

And in Gaza, a lone Palestinian gunman opened fire at the Erez checkpoint between Israel and Gaza, killing a border policeman before he was shot dead by an Israeli tank, both the army and Palestinian sources reported. The Al Aqsa Martyrs Brigade militia, an offshoot of Arafat’s mainstream Fatah faction, claimed responsibility for the attack.

Israel launched the March 29 invasion of West Bank towns and villages after a string of deadly suicide bombings, and the military offensive has enjoyed widespread popular support here. But reports of heavy bloodshed and wanton destruction in the Jenin camp, coupled with images of devastated Palestinian cities locked down under military curfew, have exacted a diplomatic price.

On Friday, Israel decided not to oppose a move in the United Nations Security Council to send a fact-finding team to determine what happened in the camp. The resolution, drafted by the United States, passed 15 to 0.

“Israel will cooperate with this team if its aim is to see what happened,” said Yarden Vatikay, spokesman for Defense Minister Binyamin Ben-Eliezer, in a telephone interview. “The truth is the best thing that could happen here.”

Palestinian officials also welcomed the decision, and Palestinian Information Minister Yasser Abed-Rabbo said he believed it was “the first step toward making Sharon stand trial before an international tribunal.”