Updated

Several Israeli tanks moved into the West Bank town of Jenin late Tuesday and Israel announced that the army would be retaking parts of Palestinian land in retribution for a deadly homicide bombing in Jerusalem.

Palestinian security officials said three tanks entered the Jenin refugee camp as attack helicopters fired from above. Palestinian gunmen fired at the tanks, they said.

There were no reports of casualties.

The move came after a Palestinian homicide bomber blew up a Jerusalem bus, killing himself and 19 Israelis.

The violent Islamic Hamas claimed responsibility for the attack and identified the bomber as Mohammed al-Ghoul, 22, from a refugee camp near Nablus.

A statement released by the Israeli government said Israel would capture and hold "Palestinian Authority territory. These areas will be held by Israel as long as terror continues. ...Additional acts of terror will lead to taking of additional areas."

The statement, issued after late-night consultations between Israeli Prime Minister Ariel Sharon and his top Cabinet ministers, said Israel was changing its response to "murderous acts of terror."

The decision to seize parts of the West Bank came with President Bush's planning to make a major Mideast policy address this week. Bush is expected to propose establishing a "provisional" Palestinian state in part of the West Bank and Gaza without deciding on its final borders — and while neither side has embraced the idea, there is some hope that a renewed and forceful U.S. diplomatic drive might help end 21 months of carnage and despair.

On March 29, following an earlier series of Palestinian homicide bombings, Israel launched its largest military mission in two decades, calling up army reserve units and sending thousands of soldiers into the West Bank, taking control of Palestinian towns and refugee camps. Hundreds of terror suspects were arrested and quantities of explosives and weapons seized, but the six-week operation won Israel only a brief respite in the bombing attacks.

Palestinians said the operation added to the frustration of the people and made it easier for violent groups to recruit homicide bombers.

Israeli forces move into Palestinian towns and villages almost every day, looking for suspects, arms and explosives.

The Associated Press contributed to this report.