"The disengagement plan will be implemented. Period," Sharon told a press conference in Israel's commercial capital Tel Aviv.

He was speaking a day after he sacked the secular Shinui party's five ministers from the coalition, leaving him with the theoretical support of only 40 MPs from his own Likud party in the 120-seat parliament.

A source close to the premier confirmed to AFP that Sharon was now trying to bring the main opposition Labour party and the ultra-Orthodox United Torah Judaism (UTJ) faction into the fold after his dismissal of Shinui.

The party's departure from government became inevitable after it voted against the first reading of a budget bill on Wednesday night, contributing to a humiliating 69-43 defeat for the government.

The defeat was not unexpected however, with many observers believing Sharon deliberately provoked Shinui by trying to channel funds into the pet projects of religious parties such as UTJ.

With Shinui now out of government, Sharon is hoping to demonstrate to opponents within his own right-wing Likud that he has no option but to invite Labour into government.

Likud's central committee voted back in August against allowing Labour into the coalition but its chairman Tzahi Hanegbi did not rule out a change of policy Thursday.

"What the central committee will surely be asked to approve is affording the prime minister the possibility of conducting negotiations and incorporating additional parties, among them the Labour Party as well as parties from our own camp," said Hanegbi, a minister without portfolio.

If he cannot bring Labour into government, Sharon will be left with no option but to call fresh elections which could derail the Gaza pullout, which should be completed next year as part of a wider so-called disengagement plan.

Sharon said if his efforts fail, "there will be no choice other than elections."

Meanwhile, jailed militant leader Marwan Barghuti electrified the race for Palestinian Authority president Wednesday as he threw his hat into the ring just hours before the close of nominations.

The candidacy of Barghuti, seen as the inspiration behind the four-year Palestinian Intifada, or uprising, was presented to the central elections commission by his wife who had earlier visited him in the Israeli prison where he is serving five life sentences.