The Israeli Cabinet on Friday approved the appointment of Ehud Barak as defense minister, an Israeli official said, capping the political comeback of the former prime minister six years after a humiliating election defeat.

The appointment follows Barak's election this week as leader of the dovish Labor Party. Barak, a former military chief, has made no secret that he coveted the defense post as a step toward returning to the nation's top job.

The Cabinet ministers approved Barak's appointment in a special vote conducted over the telephone, the official said. Prime Minister Ehud Olmert wanted the vote taken before he heads to the United States on Saturday, the official said, speaking on condition of anonymity because he was not authorized to talk to the media.

Barak's appointment is expected to receive final approval in the Israeli parliament on Monday, the official said.

Shortly after Friday's vote, the current defense minister, Amir Peretz, announced his resignation, saying he would step down after next week's parliamentary vote.

"Defense Minister Amir Peretz will resign immediately after the Knesset vote on Monday," his office said in a statement. "Until then, he will fulfill his duty as usual."

Barak's presence in the Cabinet is expected to give a boost to Olmert, who was widely criticized for his performance during last year's war against Hezbollah guerrillas in Lebanon.

While calling for Olmert to resign over the war, Barak is expected to keep Labor in the government coalition for the time being to help burnish his leadership credentials.

Earlier this week, Barak called for unity and pledged to restore Israel's military might and deterrent power.

Barak served as prime minister from 1999 until he was crushed by hard-liner Ariel Sharon in a 2001 election, months after the outbreak of the second Palestinian uprising and his failure to secure final peace deals with Syria and the Palestinians.

Barak, 65, disappeared from politics after his political drubbing, earning millions on the lecture circuit and advising businesses.

Seen as arrogant and overbearing when he was premier, Barak says he learned from his mistakes and would make a far better leader this time around.

Peretz, a former union leader with scant military experience, was trounced as Labor's leader in a first round of voting on May 28. Like Olmert, he has been widely criticized for his performance during the war. Peretz is expected to receive a lower-profile Cabinet post.