http://www.nytimes.com/2011/01/15/world/europe/15italy.html?src=mv ROME â€” Prime Minister Silvio Berlusconi faces investigation in a prostitution case involving an under-age nightclub dancer, prosecutors announced Friday, a day after Italyâ€™s highest court weakened a law that had shielded him from prosecution while in office. The office of the Milan prosecutor, Edmondo Bruti Liberati, asserted in a statement that Mr. Berlusconi had illegally compensated the minor for sexual relations during encounters at the prime ministerâ€™s private villa outside Milan. Mr. Berlusconiâ€™s lawyers dismissed the accusations as â€œabsurd and unfounded,â€ though they were certain to compound a particularly difficult time for the prime minister, whose coalition has been worn down by months of infighting that has left him with a bare majority in Parliament. The ruling by the Constitutional Court that revoked automatic immunity for the prime minister further weakened him. Even so, earlier accusations of impropriety have not disenchanted voters who have kept Mr. Berlusconi in politics for almost 17 consecutive years, and there was no sense that this most recent scandal would cause his downfall. â€œItalians have become used to this kind of news, so this will have no impact on the public that supports Berlusconi; it will only increase tensions between him and the judiciary,â€ said Roberto Dâ€™Alimonte, a political science professor at Luiss University in Rome. â€œWeâ€™ve seen so many of these things, the public opinion thinks this is just one more.â€ The prostitution case involves a girl named Karima el-Mahroug, who is better known in Italy by her nightclub stage name, Ruby Rubacuori (Ruby Heart-stealer), who was detained last May on allegation of theft. The episode became public in November, when it emerged that she had been released from police custody after a telephone call from the prime minister. She was 17 years old at the time. Prosecutors are also investigating whether Mr. Berlusconi abused his power when he intervened to have her released. Mr. Berlusconi has been summoned to appear before prosecutors in Milan this month. â€œI canâ€™t wait to defend myself in court from such absurd accusations,â€ Mr. Berlusconi said in a live audio message posted Friday evening on the Web site of his supporters, Promotori della Liberta. The investigation, he said, was â€œbased on nothingâ€ and he accused politicized prosecutors of persecuting him and trying to â€œsubvert the fundamental rules of democracy.â€ His lawyers, Niccolo Ghedini and Piero Longo, played down what they said was an intentionally headline-grabbing investigation that would probably be dismissed because the accusations had â€œalready been fully deniedâ€ by all the people involved. Pledging to reform the judicial system so that citizensâ€™ right to privacy would be respected, Mr. Berlusconi said the investigation was an â€œinterference in my private life that has no precedence in the history of this country.â€ Indeed, Mr. Berlusconiâ€™s private life has been a mother lode for prosecutors. His business dealings have led to dozens of investigations â€” from which he has emerged practically unscathed â€” though he is currently on trial in separate cases in Milan on charges of corruption, tax fraud and embezzlement. Mr. Berlusconi, a billionaire, said in the audio statement that the only people who were happy as a result of his legal travails were his lawyers. â€œTheyâ€™re sure that with me theyâ€™ll never be out of a job,â€ he said. His personal life has also become tabloid fodder, especially since he split from his wife, Veronica Lario, who filed for divorce in May 2009 after 19 years of marriage. Since then, the Italian media have had a heyday reporting that he has had dalliances with prostitutes, that aspiring models call him Daddy, and that flocks of young women, including minors, attend lively parties at Mr. Berlusconiâ€™s private residences in Rome, Sardinia and Arcore, outside of Milan. In interviews, Ms. Mahroug has said that she lied about being under age and denied having sex with the prime minister. She turned 18 in November. In a statement on Friday, Mr. Berlusconiâ€™s lawyers said it was untrue that Mr. Berlusconi had been intimate with Ms. Mahroug. Yet in the statement from the prosecutorâ€™s office she is named as the injured party. In Italy, the age of consent is 14, but favoring or exploiting prostitution of minors under 18 is a crime. A member of Mr. Berlusconiâ€™s People of Liberty party is also under investigation, as are a well-known talent agent and the news director of one of Mr. Berlusconiâ€™s television channels, the ANSA news agency reported. Mr. Berlusconiâ€™s supporters rallied around the prime minister on Friday, accusing the Milanese prosecutors of pursuing a political agenda bent on ruining Mr. Berlusconi that could have more widespread ramifications. Are Milanese prosecutors â€œfully aware of the incalculable damage that this episode wreaks not on the prime minister, but on the image of Italy and Italians around the world in such a delicate moment for the economic and financial stability of the country?â€ asked Daniela SantanchÃ©, a junior cabinet member. Analysts said, however, that for the moment Italyâ€™s fractured center-left opposition posed few real threats to the prime minister. â€œHeâ€™s still in a relatively strong position, and were elections to be called tomorrow heâ€™d still win, Ruby or no Ruby,â€ Professor Dâ€™Alimonte said.