Israel's right-wing Likud leader Benjamin Netanyahu called yesterday for an early election to replace Prime Minister Ehud Olmert, whose pledge to resign has deepened uncertainty over Middle East peacemaking.

Top advisers said Mr Olmert could stay in office for months as caretaker premier, long enough to pursue talks with the Palestinians and Syria.

But politicians said the scandal-plagued leader had no mandate to commit Israel to any deals.

"He has no legitimacy, not from the public, nor the Knesset, nor the government, to reach any understandings with the Palestinians or with Syria that would bind the government," said Communications Minister Ariel Attias of the ultra-Orthodox Shas party, a member of Mr Olmert's governing coalition.

Mr Olmert said on Wednesday he would step down after a September 17 vote within his centrist Kadima party to choose a new leader. Foreign Minister Tzipi Livni has emerged as the leading candidate inside Kadima to succeed Mr Olmert, but opinion polls show more Israelis would support Netanyahu, a vocal critic of the government's peace moves, in a parliamentary election.

It could take months for a new Kadima leader to assemble a coalition majority, and Vice Premier Haim Ramon told Channel Two TV that Mr Olmert could remain in office as caretaker until February or March, assuming new elections are called.

An Israeli official, speaking on condition of anonymity, said Mr Olmert would seek a statehood agreement with Palestinian President Mahmoud Abbas "during the time he has left" in office.

Ms Livni, Israel's chief negotiator with the Palestinians, said in New York that the negotiations were continuing despite Mr Olmert's announcement.

But analysts said it was not realistic to expect Mr Olmert to succeed in clinching sweeping peace accords. "Who is going to make a deal with him when they know he can't deliver? He is a lame duck," professor Gadi Wolfsfeld of Hebrew University said.

Speaking in Tunisia, Mr Abbas pledged to work with Mr Olmert and his successor despite the "turmoil" in Israel.

Four Kadima ministers have launched campaigns to replace Mr Olmert in the September 17 vote.

Ms Livni's closest rival for the post is Transport Minister Shaul Mofaz, a former defence chief known for his tough tactics in crushing a Palestinian uprising.