By Manuela D'Alessandro

MILAN (Reuters) - Italian judges on Friday postponed a hearing in former Prime Minister Silvio Berlusconi's "bunga bunga" sex trial after the media mogul checked into hospital with an eye condition.

The trial, on charges he had sex with an underage prostitute, is seen as the most damaging of three cases currently against him as he fights for his political future following last week's inconclusive election.

The case was entering it final stages when his lawyers asked for an adjournment to allow him to get treatment.

Prosecutor Ilda Boccassini told the court she suspected the move was a delaying tactic and asked for an independent check on his condition.

But Judge Giulia Turri and two colleagues accepted Berlusconi had a legitimate reason for a postponement and moved the hearing to Monday.

A final ruling in the case had been expected on March 18 but it was not clear if the adjournment would cause a delay.

Berlusconi has always denied any wrongdoing, and said on Thursday that all the charges against him were "judicial persecution... which re-emerges every time there are politically complex moments in the political life of our country."

He fell short of a victory in last week's vote, even though he rallied his supporters and performed better than expected. The vote ended with a hung parliament and the president is still struggling to form a new government.

Berlusconi has a condition that causes "pain, intolerance of light and disturbed vision" that is best treated in hospital, Berlusconi's personal doctor, Alberto Zangrillo, told reporters.

"He's in day hospital treatment now, but he probably will spend the night as a precautionary measure." By law, the 76-year-old billionaire has a right to be present at all his trial hearings.

On Monday, the prosecution in the sex trial said parties at Berlusconi's Milan villa were arranged for prostitution and were not the elegant dinners he suggested.

The parties involved dinner, erotic "bunga bunga" dancing and then sex between aspiring female TV stars and invited guests, prosecutor Antonio Sangermano said.

JAIL TIME

Lawyers for the owner of the country's biggest private broadcaster, Mediaset, have also asked that a hearing scheduled for Saturday in another trial be postponed because of his eye problem.

In that trial, Berlusconi is appealing against a four-year jail sentence for tax fraud in connection with the purchase of broadcasting rights by his television network.

Under Italian law, Berlusconi will not serve any jail time until the appeals process is exhausted, and a higher court could overturn the ruling.

Berlusconi was convicted three times during the 1990s, before being either cleared by higher courts or benefiting from the statute of limitations by which cases expire if a final verdict is not reached within a given time period.

On Thursday, an Italian court sentenced Berlusconi to one year in jail over the publication by his family's newspaper of a transcript of a leaked wiretap connected to a banking scandal in 2006.

In that case, the statute of limitations for the charges expires in September, before the appeals process can be completed, legal sources said.

(Reporting by Manuela D'Alessandro; Writing by Steve Scherer and Catherine Hornby; Editing by Andrew Heavens)