Israeli tanks and armored personnel carriers entered Ramallah and took up positions around Yasser Arafat's compound early Monday in a move that expands the scope of Israeli incursions into Palestinian-controlled territory in the West Bank.

Seventeen tanks established positions around Arafat's compound and just inside at a helicopter pad. Israeli soldiers flashed V-for-victory signs while standing atop their moving vehicles.

According to Palestinian intelligence officials, Israeli forces had taken over Ramallah and the surrounding area in an operation involving 130 tanks.

Two Israeli helicopters covered the incursion from above, although there was no resistance. The Israeli army spokesman's office would not immediately comment.

Within an hour of moving into Ramallah and adjoining el-Bireh, soldiers announced through loudspeakers that a curfew had been imposed on the area's 200,000 residents as in the other towns.

Israeli troops have taken control of most of the Palestinian population centers in the West Bank, placing resident in cities like Nablus, Jenin, Tulkarem and Bethlehem under curfew.

The incursions come after back-to-back homicide bombings in Jerusalem that killed 26 Israelis Tuesday and Wednesday. Israel's Cabinet said troops would seize and hold Palestinian areas until the attacks ceased.

Moments before the Israeli incursion Monday, word emerged that Palestinian authorities had placed the spiritual leader of the Islamic militant group Hamas under house arrest in the Gaza Strip. On Sunday, the Palestinians arrested dozens of Hamas members, including a local Gaza leader, Muhammed Shuhab. Hamas has claimed scores of homicide bombings in Israel.

An order had been issued for the house arrest of Sheik Ahmed Yassin, Palestinian security sources told The Associated Press. Seven Palestinian police cars blocked the street on either side of the Gaza home of Yassin, who has been placed under house arrest in the past.

In Ramallah, Arafat was inside the compound along with Faisal Abu Sharakh, head of Force 17, one of Arafat's security apparatus. Also in the compound were intelligence chief Tariq al-Tarawi, who is wanted by Israel, and Ribhy Arafat, the Palestinians' senior official responsible for coordination with the Israelis, Arafat aide Nabil Abu Rdeneh said.

"A large number of tanks and Israeli jeeps are surrounding the president's office from all sides," Abu Rdeneh told The Associated Press from inside the compound.

Since the end of March, when Israeli forces bombarded the compound and stayed there for a month, they have been back three times. Earlier this month, they blew up some buildings inside the compound and left the same day. They also returned two weeks ago, staying around the compound for three days before leaving.

Early Monday, witnesses said two Israeli army jeeps pulled up outside al-Amari refugee camp next to Ramallah and three parked in front of the government hospital.

A few bursts of machine-gun fire were heard near the refugee camp, apparently soldiers announcing their presence rather than exchanges of fire. About an hour later, three explosions were heard and white puffs of smoke rose from inside the camp. It wasn't immediately clear what had been hit.

Israeli officials deny Arafat's claim they intend to re-establish civil control over the West Bank, making Israel again responsible for municipal services, building permits, education and vital records. An Israeli military administration presided over Palestinians until creation of autonomous areas began in 1994.

"It is clear that this is a continuation of the occupation in our towns and refugee camps," Arafat said Sunday.

Raanan Gissin, spokesman for Israeli Prime Minister Ariel Sharon, said that "Israel will be there in military presence only, in order to crush terror," Gissin said. He acknowleged, however, that Israel would assist when necessary.

Prime Minister Ariel Sharon's Cabinet approved a security plan that includes building concrete barriers and electronic fences in hopes of preventing attacks on its territory.

Israeli Cabinet Secretary Gideon Saar said the government was considering the possibility of deporting families of Palestinian homicide bombers to the Gaza Strip, but would not act unless the Israeli judiciary said such action was legal.

"The position of the Israeli government is that the terror of suicide bombers ... obligates the consideration of unconventional means," Saar said.

Israeli forces moved into the West Bank town of Qalqiliya at daybreak Sunday. Also Sunday, the army began drafting a brigade of about 4,000 reserve troops to deal with the West Bank incursion, army officials said.

Two Palestinian police officers were killed Sunday, one when army forces entered al-Yamun village near Nablus and the other when an Israeli tank shell hit a building in the Tulkarem refugee camp. Palestinian witnesses said children were throwing stones at the tank. The army did not comment on either death, but said Palestinian gunmen in Tulkarem fired on Israeli forces.

Also, an Israeli officer wounded in a June 15 Palestinian attempt to infiltrate a Jewish settlement in Gaza died of his injuries, the army said.

Speaking after the weekly Cabinet meeting, hard-line Israeli Cabinet Minister Effi Eitam said Israel was at war and would remain in Palestinian areas "for many months, responsible for security there."

"For all practical purposes, Oslo died a long time ago," he said, referring to 1993 peace deal founding the Palestinian Authority. "None of the agreements exist anymore."

Israel's Cabinet officially approved a security plan establishing buffer zones around Palestinian areas in the West Bank, Saar said. The plan includes the security fence already being built, in some areas, along Israel's unmarked border with the West Bank.

Israeli officials deny the barrier is a precursor to a border, insisting the fence is being built for security reasons.

The Associated Press contributed to this report.