Mr Sharon is Prime Minister's Binyamin Netanyahu's closest political ally and initially urged colleagues to support their Likud Party leader.

But just two days after publicly backing Mr Netanyahu he told a television talk show he might run for prime minister if there were "special circumstances".

He did not say what those circumstances might be or if he planned to challenge Mr Netanyahu for the Likud Party leadership or form his own party.

Early elections are to be held on 17 May after Mr Netanyahu lost support of right-wingers for his handling of the peace process.

They accused the prime minister of betrayal over the Wye River deal, which agreed to give up West Bank land in return for Palestinian security guarantees.

Netanyahu criticised

In a further blow to Mr Netanyahu's authority, Defence Minister Yitzhak Mordechai has criticised the prime minister for subsequently suspending the peace agreement.

Mr Mordechai, the country's most popular politician in opinion polls, also warned he was considering his future with the ruling Likud Party.

Amnon Shahak: Tipped to enter race

He told Israel Army Radio: "For today, I am a Likud man. If I reach a different conclusion, I'll let the public know."

Five candidates are already in the race to be prime minister and the recently retired armed forces chief of staff, Amnon Shahak, is expected to announce soon that he will also run.

Other candidates include Ze'ev Binyamin Begin, the son of the former prime minister, Menachem Begin, and Dan Meridor, a moderate who resigned as finance minister in June.