Bethlehem, West Bank ? Israeli troops backed by armor intensified an offensive across the West Bank on Monday, pounding a Ramallah building with anti-aircraft guns, briefly pushing into Bethlehem and sending the deafening echo of tank shells through Palestinian streets.

Spurred by a wave of bloody suicide attacks that claimed more than 40 lives in five days, Israeli leaders said the military drive was meant to smash a Palestinian terrorist infrastructure. Palestinians, for their part, said Israel’s tactics amounted to a campaign of state terror against the civilian population.

Troops searching for Palestinian militants and weapons caches carried out house-to-house searches and engaged in running battles with gunmen. In the center of Ramallah, soldiers used vehicle-mounted antiaircraft guns to pulverize the facade of a building where Palestinian gunmen were holed up, sending chunks of masonry plunging into the street.

Israeli forces also moved into the northern Palestinian towns of Qalqilya and Tulkarem on Sunday night and Monday.

In the sixth Palestinian attack in six days, a car bomb exploded near downtown Jerusalem. Police said a policeman stopped the car and the driver, a Palestinian, set off the bomb. The Palestinian was killed and the policeman seriously injured. The Al Aqsa Brigades, a militia linked to Palestinian leader Yasser Arafat’s Fatah movement, claimed responsibility.

Sporadic gunfire rang out after dark in Ramallah, a few miles to the north, where a tight curfew and continued fighting have turned a busy commercial center into a ghost town. The boom of tank shells was heard after night fell. Eight Israeli soldiers were injured  two seriously  in Ramallah and another in Qalqilya, a military source said. The bodies of two Palestinian police were found in a park in the city’s center, Palestinian military intelligence said.

Among the fugitives being hotly pursued by Israeli forces in Ramallah was Palestinian militia leader Marwan Barghouti, a senior Israeli security source said, speaking on condition of anonymity. Israeli officials have said Barghouti was involved in numerous deadly attacks on civilians.

Palestinian leader Yasser Arafat, whom Israel blames for one of the worst waves of suicide bombings since the start of the conflict 18 months ago, was trapped in Ramallah headquarters for a fourth straight day, pinned down by Israeli troops and tanks within the walls of his compound.

President Bush called on Arafat to put a stop to anti-Israeli attacks. “There will never be peace so long as there is terror, and all of us must fight terror,” Bush said.

Israeli soldiers set up more barricades in Ramallah’s streets, turning cars already smashed by tanks onto their sides to form roadblocks. Pressing ahead with searches, Israeli soldiers broke down the doors of homes in Ramallah and Qalqilya, Palestinians said.

“They smashed pictures that were on the wall and looked everywhere, emptying closets and throwing around our clothes,” said 26-year-old Nafiza Rouf, who said soldiers spent about two hours in her Ramallah house. Her 24-year-old brother Niad was made to kneel motionless while soldiers shouted questions and abuse at him, the family said.

A group of Palestinian boys, some as young as 9 or 10, drew live fire from Israeli soldiers in downtown Ramallah when they lit a bonfire of tires and hurled stones in the direction of troops  though their rocks fell far short of the mark.

An 11-year-old Palestinian boy was killed by gunfire from Israeli soldiers as he played near a market in Rafah, in the Gaza Strip, Palestinian hospital officials said.

In Ramallah, nearly all the dead over the course of the incursion  at least 25, by Palestinian count  have been men in their 20s and 30s. At Ramallah Hospital, the city’s main medical center, doctors pulled open the metal doors of the morgue to display bloodied bodies of the young men, wrapped in sheets, and said they had not been allowed to transport them out for burial.

“Almost everyone we get is dead  not wounded, but shot dead on the spot,” said an emergency doctor, Mohammed Butrawi.

The day’s widening offensive began before dawn when tanks rolled into Bethlehem, just five miles south of Jerusalem. The tanks stopped about 500 yards short of the Church of the Nativity, built over the traditional birthplace of Jesus. An Israeli soldier was shot and killed by a Palestinian sniper, the military said. Troops also moved into the nearby villages of Al Khader and Beit Jalla.

The Israelis pulled back to the edge of Bethlehem later in the day, but about 40 Israeli tanks and armored personnel carriers were poised on the edge of town, and townspeople were bracing for another incursion.

In Beit Jalla, Israeli forces imposed a curfew and occupied buildings overlooking Bethlehem.

Six foreigners protesting the Israeli invasion were injured when they marched up to tanks in Beit Jalla, said doctors. One woman was hit in the stomach by a bullet, and witnesses said the others were struck by shrapnel after an Israeli soldier fired into the ground. An Associated Press Television News cameramen, Iyad Hamad, was also lightly injured. The military would not immediately comment on the incident.

State Department spokesman Philip Reeker criticized Israel for injuring the protesters and said the military should investigate the incident to prevent such incidents in the future.

Israeli military officials said the Operation “Protective Wall” could be lengthy. “We are defending our homes. We have no other place. We are going to defend our homes with all our strength,” Defense Minister Binyamin Ben-Eliezer said Monday.

Palestinian Cabinet Minister Saeb Erekat accused Bush and the United Nations of ignoring the Palestinians’ suffering. “There is total destruction, total state terror against the Palestinians,” Erekat told The Associated Press.

As Israeli forces advanced, Palestinian militants were killing Palestinians suspected of collaborating with Israel. Ten bodies were found in the West Bank, including seven taken by militants from a temporary jail and shot in the streets of Tulkarem.

A gathering of Islamic nations in Malaysia condemned Israel’s offensive and urged the United Nations to intervene to protest Palestinians.