Prime Minister Ariel Sharon called on his defeated dovish rivals Sunday to join him in a broad-based government but they said they remain unconvinced he is seriously pursuing peace with Palestinians.

Sharon's appeal came several days after he renewed diplomatic contacts with senior Palestinian officials -- a move skeptics said primarily was a nod to the Americans and to the opposition Labor Party.

So far, Labor has refused to consider re-entering the "unity" government it left in November. That move prompted last month's elections in which Sharon's Likud party and his hawkish allies won a majority.

Labor leaders insist the retired general has no plan for restarting peace talks and say they will not provide cover for his crackdown on the Palestinians.

But the unity idea is extremely popular in Israel, where polls show a solid majority does not want Sharon to establish a coalition with his natural allies -- nationalist and Orthodox Jewish parties opposed to Palestinian statehood and territorial concessions.

With Labor as his partner, Sharon would have more room to maneuver and could move ahead -- as he says he is willing to do -- toward the provisional Palestinian state envisioned by President Bush.

"Whoever wants peace must either enter the government or take responsibility for his refusal," Sharon said. "Those who say 'no' to unity defy the will of the Israeli public."

His comments came at a ceremony where Israeli President Moshe Katsav assigned him the task of forming a new government -- a formality.

In secret talks last week with senior Palestinian negotiator Ahmed Qureia, Sharon proposed that Israeli troops withdraw from Palestinian areas where militants have been subdued by Palestinian security forces, said senior Sharon aide Dov Weisglass, who attended the meeting.

Similar arrangements have failed in the past, partly because Palestinian security forces weakened by Israeli military strikes have lost control in many areas of the West Bank and Gaza Strip.

Labor lawmaker Danny Yatom said the meetings were a welcome development, but not enough.

"These things are still not evidence that there is the will and the intention to move forward," he told Israel Radio. "I'm waiting to see the results of these meetings."

Violence continued despite the diplomatic efforts.

In Gaza, three Palestinians were killed when their explosives-laden car blew up outside an Israeli army post after crashing into a cement-block barrier. Four soldiers were slightly hurt. The group Islamic Jihad claimed responsibility.

Fighting erupted in September 2000, burying peace talks and bolstering support for Sharon, a career hard-liner and patron of the Jewish settler movement. Since then, 2,092 people have been killed on the Palestinian side and 722 on the Israeli side.

Sharon and his allies control 69 seats in the 120-seat parliament. Labor, whose governments spearheaded a decade of failed peace talks, has only 19 seats.

Sharon, who has six weeks to form a government, said Israel's crisis was compounded by the possibility that Israel would be dragged into a U.S.-led war against Iraq.

"The campaign by the United States against the tyrant who threatens our security and the security of the world represents a threat, but at the same time should mark a great opportunity," he said, predicting a diplomatic push to face the threat of international terrorism.

Meanwhile, Egyptian President Hosni Mubarak told Egyptian television he might invite Sharon to the Red Sea resort of Sharm el Sheik "when he forms his government and we know what it looks like."

Mubarak met Sunday in Sharm el Sheik with the leaders of Libya and Syria to discuss the Iraq crisis.