JERUSALEM — Angered over the resumption of Israeli-Palestinian peace talks, a hawkish and outspoken Israeli legislator withdrew his party from the governing coalition on Wednesday, leaving Prime Minister Ehud Olmert with a significantly slimmer majority in Parliament.

The action by the legislator, Avigdor Lieberman, was not a surprise, but it led to fresh speculation that a period of intensified political tumult loomed in Israel. The withdrawal of the 11 members in his party, Yisrael Beiteinu, leaves the coalition with 67 of Parliament’s 120 seats.

The restarting of peace talks had no effect on Israeli-Palestinian violence, which continued Wednesday. Israeli forces killed three Palestinian civilians in Gaza, among them a boy, 14, during what the Israelis called a botched missile attack on a vehicle carrying gunmen.

Later, two militants were killed in an Israeli airstrike on their car in the central Gaza Strip, Palestinian hospital officials said. The Israeli Army said that the car, carrying members of the Popular Resistance Committees, was loaded with weapons.

Palestinian militants from Gaza fired more than 40 Qassam rockets and mortar shells at Israel, Israeli Army officials said, with more than 20 of them actually landing in Israel by the early evening, causing some damage to property, but no casualties.

Early Wednesday, Israeli forces killed a senior commander of Islamic Jihad in the West Bank in a firefight while trying to arrest him, according to military officials and Palestinian reports.

Islamic Jihad threatened “a painful reaction,” while Hamas, the Islamic group that controls Gaza, claimed credit for the heavy rocket and mortar fire, raising tensions further after an Israeli Army operation in Gaza on Tuesday killed 18 Palestinians, mostly members of the military wing of Hamas.

Israeli military officials said the senior Islamic Jihad commander, Walid Obeidi, 46, who was killed in Qabatiya, in the northern West Bank, had been “involved in intense terrorist activity” since the 1980s, and had planned numerous suicide attacks.

The three civilians killed in Gaza were from one family. Maj. Avital Leibovich, an Israeli Army spokeswoman, said their car was “unintentionally hit” during an army operation against another vehicle carrying gunmen “responsible for rocket launchings.” She said the army was investigating the deaths.

Mr. Lieberman had threatened to leave the coalition once Israel’s talks with the Palestinians touched on the contentious core issues of the Israeli-Palestinian conflict, including borders, refugees and the status of Jerusalem. The Israeli government and the Palestinian leadership based in the West Bank, which is alienated from Hamas, officially started those talks on Monday.

At a news conference in the Parliament building on Wednesday morning, Mr. Lieberman said he did not expect the Israeli-Palestinian negotiations to lead anywhere, but added, “I have said tens of times that our job in government was to stop the Annapolis process.” He was referring to the American-sponsored peace conference in late November in Annapolis, Md., which created the basis for the talks.

Mr. Olmert accepted the resignation of Mr. Lieberman, who had served as minister of strategic affairs, a portfolio specially created for him when he joined the government in October 2006.

In a statement issued by his office, Mr. Olmert said that “there is no alternative to conducting serious diplomatic negotiations in order to reach peace” and that he was “determined to continue the diplomatic negotiations out of recognition that they contain the only real chance to assure the peace and security of Israel’s citizens.”

Mr. Lieberman’s departure may signal some political upheaval ahead, coupled with the final report of a committee that investigated the leadership’s handling of the 2006 war in Lebanon, set to come out in two weeks. The committee, headed by Eliyahu Winograd, a retired judge, issued a highly critical interim report last spring, prompting calls for Mr. Olmert’s resignation.

Defense Minister Ehud Barak, the leader of the leftist Labor party and a major coalition partner, suggested months ago that he would work to form a new government or to set a date for early elections once the final report came out. But some Israeli political commentators said it would be hard for Mr. Barak to break up a government dedicated to peace, with Mr. Lieberman out.

Mr. Lieberman, who espouses a hard line toward the Palestinians, said on Wednesday that he advocated a solution based on “exchanges of territory and populations,” adding that the Arab citizens who make up 20 percent of Israel’s population presented more of a danger to the Jewish state than the Palestinians in the West Bank and Gaza.

One veteran Israeli Arab legislator, Ahmed Tibi, said that Mr. Lieberman “gives racists around the world a bad name.”

Copyright 2008 The New York Times Company