Israeli forces killed two Palestinian gunmen in a battle Tuesday near the West Bank city of Jenin, while fighting between Palestinian factions in the Gaza Strip renewed the possibility of a broader conflict as Israel prepares to evacuate its settlers from the area next month.

Elsewhere, thousands of Israeli demonstrators opposed to the withdrawal plan confronted a police cordon intended to keep them from marching to the largest Jewish settlement area in Gaza.

March organizers had hoped to enter the area with tens of thousands of protesters and block the evacuation, scheduled to begin Aug. 15. But Israeli security officials banned the march, and demonstrators remained stalled Tuesday in the town of Kfar Maimon in a standoff with 15,000 police officers. Israeli police reported arresting 16 demonstrators.

The day's events reflected the internal tensions within the Israeli and Palestinian camps as the Israelis prepare to evacuate 21 Gaza settlements and four others in the northern West Bank in an operation known as disengagement.

Prime Minister Ariel Sharon has said the withdrawal will not be threatened by Palestinian attacks or by Jewish extremists, who have resorted to sabotage, called on soldiers to disobey evacuation orders and engaged in mass civil disobedience in hopes of derailing the operation.

"We will not allow any terrorism before disengagement or following disengagement, so we are starting now," said Raanan Gissin, a spokesman for Sharon, referring to the move against Palestinian gunmen. "At the same time we will have zero tolerance toward sedition."

With increased rocket attacks on Israeli targets threatening the planned withdrawal, Palestinian leader Mahmoud Abbas has ordered his security forces to act against the military wing of Hamas, a radical Islamic group that rejects peace negotiations with Israel. The move has brought the mainstream Palestinian security services, dominated by Abbas's ruling Fatah organization, into direct armed conflict with its chief political rival.

Hamas has fired more than 100 rockets and mortar shells into Gaza settlements and southern Israel in recent days, killing a 22-year-old Israeli woman and wounding more than a dozen other people. Although Hamas has refused to renew its commitment to a five-month-old cease-fire, the rocket attacks have tapered off. Scores of Israeli tanks remained massed along the Gaza border Tuesday.

Before dawn Tuesday, Palestinian security services raided a building identified as a Hamas educational center north of Gaza City. The police seized computers and documents, witnesses said, before coming under fire from Hamas gunmen. Six people were wounded, while two Hamas-affiliated offices and at least two cars were burned.

[Fatah and Hamas ordered a truce in the Gaza Strip early Wednesday, the Reuters news service reported.]

Meanwhile, in the West Bank city of Yamoun, near Jenin, Israeli soldiers encircled a house looking for two members of Islamic Jihad sought by Israel. The group has asserted responsibility for a suicide bombing in the Israeli town of Netanya last week that killed five Israelis.

After the men refused to surrender, an Israeli military bulldozer moved to destroy the house, Israeli military officials said. The men inside opened fire with rifles and grenades, military officials said. The men, whom the Israeli military said helped plan several suicide bomb attacks and attempts, were killed when Israeli soldiers returned fire. The military identified them as Ibrahim Abhara, 28, and Warad Abhara, 27.

"What Israel is doing is madness," said Zakaria Zbeida, commander in Jenin of the al-Aqsa Martyrs Brigades, a militant group associated with Fatah. "It seems that Israel is trying to bring about an escalation, through assassinations and arrests, so that it won't have to withdraw from the four settlements in the Jenin area. Unfortunately, this cycle of violence is not good for the Israeli public or the Palestinian public."

Researcher Samuel Sockol contributed to this report.