Updated

Hamas quit talks Friday on halting anti-Israeli attacks, a decision that jeopardizes the U.S.-backed peace plan. But Palestinian officials insisted a truce was still possible and pushed ahead with plans to get illegal guns off the streets, including a weapons buyback.

As part of the U.S.-backed "road map" to Palestinian statehood (search), the Palestinians have to disarm and dismantle militant groups that have killed hundreds of Israelis in shootings and bombings in 32 months of fighting.

Palestinian Prime Minister Mahmoud Abbas (search) has been trying to negotiate with the militias rather than use force, and said earlier this week he was optimistic he could broker a truce within a week.

Hamas (search) refusal to negotiate could force Abbas to make a difficult choice: either crack down on the group and risk civil war, or allow it to continue bombings and shootings that would derail Washington's peace efforts.

The White House underlined that Palestinian leaders must still ensure a stop to attacks on Israel.

"There is now a real prospect for peace," said Michael Anton, a spokesman for the White House's National Security Council. "All parties agreed ... that terrorism has to stop and that all parties have an obligation to fight terror. Those who pursue terror have made it clear they want to prevent peace."

Palestinian officials say the Hamas walkout may not be final. Hamas, known for its pragmatism, would not risk a confrontation with security forces and would quickly resume talks, they said.

Palestinian Cabinet Minister Ziad Abu Amr, Abbas' liaison to Hamas, blamed Israel's overnight killing of two Hamas militants near the West Bank city of Tulkarem for the breakdown in talks.

Hamas officials, however, said they were angry at Abbas' concessions at a Mideast summit Wednesday in Jordan. At the meeting with President Bush and Israeli Prime Minister Ariel Sharon, Abbas, also known as Abu Mazen, called for an end to the "armed intefadeh."

"We were shocked when we saw Abu Mazen and his new government giving up all the Palestinians' rights," said Abdel Aziz Rantisi (search), a Hamas official. "Abu Mazen committed himself in front of Bush and Sharon to very dangerous issues that closed the door of dialogue between us."

Other efforts to clear the streets of gunmen continued, with Palestinian security chief Mohammed Dahlan offering to buy illegal weapons carried by members of the Al Aqsa Martyrs' Brigades, a militia linked to Abbas' Fatah movement, according to several Palestinian officials and militia members. The buyback was to start in the coming days, they said.

Dahlan has received money from the United States and Europe to buy the weapons, the officials said.

Britain's Foreign Office, however, said Friday the government had not provided any money, though it was aware of the buyback plans and was prepared to help in any initiative improving prospects for peace, according to a spokeswoman in London. U.S. officials did not respond to requests for comment.

An Al Aqsa leader said Dahlan is offering $6,000 -- more than twice the black market value -- for each rifle, though officials gave lower figures. Dahlan also offered a signup bonus of at least $6,000 to Al Aqsa members who leave the militia and join the security forces, militiamen said.

Those amounts are enormous in the West Bank and Gaza, where a teacher makes about $330 a month, and unemployment is over 50 percent.

In a leaflet, Al Aqsa said it would only lay down its arms if Israel stopped killing and arresting its leaders and released prisoners. The group also demanded Israel lift a travel ban on Yasser Arafat, in effect for more than a year, that confines him to the West Bank.

But the real difficulty for Abbas' disarmament efforts likely lies with the more hard-line Islamic groups.

Hamas, founded in 1987, is vehemently opposed to peace with Israel and has strong support in the Gaza Strip, where supporters held a series of rallies Friday. In the largest, more than 4,000 Hamas supporters protested the summit, some chanting "Abu Mazen the homeland is not for sale."

Hundreds of other Hamas activists demonstrated in Lebanon.

Hamas official Ismail Abu Shanab said members of the group planned to meet Saturday with Islamic Jihad, a smaller militant group, and ask it to end their cease-fire talks as well. Mohammed Hindi, an Islamic Jihad spokesman, said it had not yet taken a position on whether to leave the talks.

Bassam Saabi, a West Bank Islamic Jihad leader, said under no conditions would his group take up arms against Abbas.

"We are brothers, we are fighting for the same goals and there is always a solution," he said. "Even if he wants to take our weapons and chase us we will hide like we do with the Israelis. We will not raise these weapons in his face. We will hide and continue our jihad."

Abu Amr said he was confident Hamas would return to the negotiations "hopefully by Sunday or Monday" and said contacts between the Palestinian leadership and Hamas leaders abroad are proceeding.

"Both the government and Hamas have no choice but to continue with the dialogue because we have both committed ourselves to avoiding internal conflict," he said.

Abu Amr accused Israel of hampering Abbas' efforts by continuing operations in Palestinian areas, including the one just before midnight Thursday in the village of Attil.

In an arrest raid, troops surrounded a house and ordered those inside to surrender, the army said. When two wanted men refused to come out, troops entered the house and fought with them. Two Hamas militants were killed and a third was wounded and arrested, the army said.