A day before a major policy address by Prime Minister Ariel Sharon (search), his ruling party appeared bitterly divided Wednesday over proposals that Israel withdraw from parts of the West Bank (search) and Gaza even without negotiating with the Palestinians.

Egyptian mediators, meanwhile, ended an unsuccessful effort to win a no-violence pledge from Palestinian militants.

Violence continued early Thursday when Israeli troops conducting searches killed four armed Palestinians in clashes in the West Bank city of Nablus, a military spokeswoman said.

Palestinian witnesses said they saw five dead bodies in the casbah, or market section, of Nablus.

The military said one man ran toward troops with an explosive device and was shot as he approached. In a separate incident, three masked men with automatic weapons shot at soldiers from a rooftop and were killed by return fire, the spokeswoman said on customary condition of anonymity.

Sharon has said Israel is committed to the U.S.-backed "road map" peace plan, which envisions an independent Palestinian state by 2005. In the interim, the plan requires Israel to freeze settlement activity in the West Bank and Gaza Strip, and calls on the Palestinians to dismantle militant groups -- moves neither side has taken.

Settlers at the outpost of Migron, north of Jerusalem, welded trailers together and blocked roads on Wednesday ahead of an anticipated army move to evacuate the outpost, where 43 families live. Rabbis who live in nearby settlements arrived to show support.

Army Radio said settler rabbis issued a religious ruling banning the government from evacuating settlements or handing over West Bank land. The ruling is not legally binding but would be respected by many Orthodox Jews.

Sharon has spoken in recent weeks of taking unspecified unilateral action if peace efforts fail. He has said such moves would not be as generous as a negotiated settlement, but indicated that they would still involve painful concessions to ensure Israel's security.

Officials who have spoken to the prime minister have said his proposals could include withdrawing from parts of the West Bank and Gaza and closing Jewish settlements in the areas evacuated.

Channel 10 TV reported that Sharon would send his speech to Washington before delivering it. A spokesman for Sharon refused to comment.

Talk of such actions has set off an impassioned debate within the Likud Party, a conservative grouping that historically has been committed to Jewish control over the biblical Land of Israel, an area that includes the West Bank.

Vice Premier Ehud Olmert, a close ally of Sharon, has come forward in recent weeks with his own calls for unilateral moves -- also as a last resort should peace efforts fail.

He said in a radio interview Wednesday that it is clear that Israel's current borders -- meaning the occupation of the West Bank and Gaza -- will have to change. A day earlier, he said that "tens of thousands" of settlers would have to be uprooted.

"I don't think we should create some fantasy, and I also don't think we should avoid the reality as it is and as we have to deal with it," Olmert told Israel Army Radio.

Also Wednesday, Palestinian sources said a 20-year-old man was killed when soldiers fired on a crowd of bystanders near a tower in southern Gaza. The army said it had shot a Palestinian gunman, but had no details on his condition.

Sharon faces considerable international and domestic pressure to end three years of fighting with the Palestinians. Many Israelis, including Olmert, also fear Israel will lose its Jewish majority if it continues to control the 3.5 million Palestinians living in the West Bank and Gaza. Israel itself has 5.2 million Jews and 1.3 million Arab citizens.

Within the Likud, however, other senior officials said a unilateral pullback would invite more violence.

Foreign Minister Silvan Shalom, speaking at a national security conference in the Tel Aviv suburb of Herzliya, called such proposals a "reward for terrorism."

The conference is the same venue where Sharon is to speak on Thursday evening.

Benjamin Netanyahu, the powerful finance minister, delivered a similar message. "For every step that you take, you have to receive a return -- concessions have to come in return for something," said Netanyahu, a former prime minister.

Netanyahu also announced that he had appropriated $160 million for the continued construction of Israel's separation barrier in the West Bank. Israel says the structure is needed to protect against suicide bombers; the Palestinians say the barrier -- which digs deep into the West Bank in some areas -- amounts to an Israeli seizure of their territory.

Talk of additional one-sided actions has also upset the Palestinians and the United States, who both say that a peace settlement must be reached through negotiations.

"It is better for us to agree on the issues to reach a permanent agreement to put an end to the conflict ... not to take unilateral steps," said Palestinian Prime Minister Ahmed Qureia, urging Sharon to honor the road map.

Since taking office in October, Qureia has been trying to arrange a meeting with Sharon, but the two sides have not been able to agree on an agenda.

Qureia has also been trying -- without success -- to secure a commitment from militant groups to halt attacks on Israel. A truce would be seen as a key first step toward resuming peace talks.

Egyptian mediators involved in the cease-fire efforts wrapped up a round of meetings with militant groups in Gaza Wednesday without making any progress, although militants agreed to continue the dialogue. Talks in Cairo earlier this month also ended without an agreement.

Egypt announced it would send its foreign minister, Ahmed Maher, on a rare visit to Israel next week to help restart peace talks.