Tel Aviv - The leader of Israeli Prime Minister Ehud Olmert's largest coalition partner threatened Thursday to support a bill calling for new elections, unless the beleagured premier's faction held early primaries to elect a new head.

"We will join the proposal, or in fact will lead the proposal, calling for the Knesset to disperse on June 25," Defence Minister and Labour Party leader Ehud Barak said.

He made the comments a day after Olmert, in a move which could lead to the end of his long political career, authorized his Kadima party to prepare for a leadership primary.

But no date was given and speculation had it that Olmert wanted to play for time in order to try fight corruption allegations.

The premier is suspected of illegally taking vast sums of money from Morris Talansky, a Jewish fundraiser and businessman from Long Island in the US, in the years before he became premier in May 2006. The investigation into the allegations is the latest of five probes the premier has faced

Although the investigation is not yet complete and Olmert has not been indicted, Talansky was permitted to give special pre-trail testimony in which he claimed Olmert had accepted hundreds of thousands of cash dollars over a 15-year-period.

His testimony was not cross-examined by Olmert's lawyers, but it was enough to spur Barak to demand, on March 28, that unpopular premier "detach" himself from the day-to-day running of the county in favour of a new Kadima leader, since he could not concentrate on the challenges facing Israel and deal with his personal affairs at the same time.

If not, Barak said, Labour would support holding early elections.

Olmert initially rejected Barak's ultimatum, and insisted that his innocence would come to light after Talansky's testimony was challenged by his lawyers, but the news conference by the Labour Party leader sparked calls for new elections to be held.

Legislator Silvan Shalom, from the opposition Likud Party, has presented a bill calling for the Knesset to dissolve itself and for new elections to be held.

However it has to pass three readings before it becomes law and analyst Calev Ben-David pointed out in the Jerusalem Post daily Thursday that Labour, and another coalition partner, Shas, have only agreed to support the bill in its preliminary passage through parliament.

"By threatening to bring down the government, Labour and Shas are really trying to force Kadima to remove its politically radioactive leader, as well as extract fresh concession from their senior coalition partner," he wrote.

Their support for the early elections bill, he said, "should not be viewed in the context of a sincere desire to face the voters anytime soon - if anything the opposite."

Polls show the Likud would beat both Labour and Kadima if elections were held now, while Shas would likely not improve on the 12 Knesset seats it currently holds. (dpa)