An Italian court ruled on Wednesday that George Clooney and Cristiano Ronaldo can be called as witnesses in ex-prime minister Silvio Berlusconi\'s trial for having sex with an underage prostitute. Lawyers for Berlusconi want the Hollywood heart-throb and Real Madrid football star to help defend their client from charges of paying for sex with a 17-year-old girl and then pressuring police to get her freed from custody. The two are being called in an attempt to discredit the woman, Karima El Mahroug, better known by her stage name as \"Ruby the Heart Stealer\", who claims Clooney was at a raunchy party she attended and says she had sex with Ronaldo. Clooney had already denied the claim and has said that he could testify. Ronaldo dismissed El Mahroug\'s assertion as \"totally false\". The two are among 78 star witnesses including several former government ministers, a Neapolitan singer and two famous starlets being called by the defence, according to the list approved on Wednesday, a court official said. Prosecutors are calling a total of 136 witnesses including Moroccan-born El Mahroug and 32 other young women who attended parties at the former premier\'s luxury villa near Milan where the underage sex crime allegedly took place. During police questioning, extracts from which have been leaked to Italian newspapers, El Mahroug recounted orgies referred to as \"Bunga Bunga\" parties describing several naked women giving the ageing billionaire lap dances. Berlusconi faces a maximum of three years in prison for the sex charge and 12 years for abuse of power, after he allegedly abused the power of his office to get El Mahroug released when she was arrested in an unrelated case. The court official in Milan said the judge would decide on a case-by-case basis whether specific witnesses would be called based on how the trial, which began in April but is still stuck in procedural issues, develops. \"Usually if they\'re called they have to come. But if they didn\'t come, we wouldn\'t send the police after them,\" the official said. The next hearing on December 2 will see the first witnesses called -- seven police officials who will testify on the abuse of power charge. The following hearings will be on December 12, January 27 and January 30.  Clooney has denied being at any raunchy soirees hosted by Berlusconi although he told Time magazine earlier this month that one party he attended was \"one of the more astonishing evenings of my life.\" Clooney said he had been called by Berlusconi\'s lawyers and had told them: \"I will come and testify if you like because I wasn\'t at the party that I was said to have been at.\" \"I wasn\'t at his bunga bunga party. But I was at another party, I went there to speak about Darfur. It was an amazing conversation. He showed me his bedroom and the bed that Putin had given him,\" he said. Berlusconi resigned earlier this month and can no longer claim his official duties as a justification to avoid hearings in the three trials he is currently a defendant in, including on charges of tax fraud and bribery. But he is still a member of parliament and therefore has parliamentary immunity, which can only be lifted by a vote in the legislature.  Even if convicted, he is unlikely to see the inside of a prison cell as people over 70 are not normally incarcerated except for murder or drug crimes. Among the other witnesses called by the defence are Argentinian showgirl Belen Rodriguez, Clooney\'s former girlfriend Elisabetta Canalis and former foreign minister Franco Frattini. Berlusconi said he had called police to have El Mahroug released when she was arrested for petty theft because he thought she was the niece of ousted Egyptian president Hosni Mubarak and did not want a diplomatic incident. Prosecutors say Berlusconi was aware of El Mahroug\'s true identity and was acting only out of fear that the girl could tell police about their liaison.