The main witness in a real-estate corruption case against former Israeli Prime Minister Ehud Olmert has been hospitalized Thursday, the proceedings came to a halt.

The witness, whose identity is under a gag order, is referred to as S.D. It is not yet certain when the proceedings will be renewed.

It is unclear yet as to the source of his medical problems, and he was hospitalized in September as well.

S.D. is the state's witness against Olmert and the trial relies mainly on his testimony against Olmert. He has given his testimony four times a week, five hours each time.

The Holyland case is one of the largest bribery and fraud schemes in the country's history, running against Olmert as well as fifteen other defendants.

It involves public officials moving ahead a deluxe residential housing project in Jerusalem while overlooking various building and zoning regulations.

Olmert at the time was the mayor of Jerusalem and then the minister of Industry, Trade and Labor.

In light of the witness' deteriorating health, Tel Aviv District Court Judge David Rozen ordered in September that the case should move forward in a new format.

Last week, local media reported that S.D. had some cracks in his story, mainly contradicting himself regarding the amount of bribe allegedly given to Olmert.

Olmert was acquitted in July from two other cases. One of them was the Rishon Tours case in which he was alleged to double-bill organizations on behalf of which he spoke abroad.

Another was the Talansky case, in which Olmert was charged with illegally receiving hundreds of thousands of dollars illegally.

However, Olmert was found guilty in breach of public trust, in the investment center affair.

He had granted personal favors to his long-time friend and ally Uri Messer and his clients, as the Minister of Industry, Trade and Labor.

The judges found there was no moral turpitude to Olmert's actions, which paved the way for him to return to politics without a hitch.

Olmert met with former political affiliate Tzipi Livni on Wednesday about returning to politics ahead of the January 22 elections.

According to a poll commissioned by the Ha'aretz daily last week, a new centrist party formed by Olmert, Livni and newcomer politician Yair Lapid will win more seats in the next Knesset ( parliament) than the right-wing bloc, led by the newly-merged Likud-Beiteinu party.