© European Pressphoto AgencyPimp: Berlusconi is accused of paying for sex with Karima El Mahroug when she was 17
Italy's Prime Minister has bounced back from countless scandals, but the latest allegations may prove disastrous

Silvio Berlusconi maintained at least 14 glamorous young women in apartments in a gated complex outside Milan, leaks from prosecutors in the city revealed yesterday. They lived rent-free in the estate and were given large sums of cash by the billionaire politician in return for sex.

Milano Due was one of the first gated housing estates in Italy, a sprawling complex of flats set in landscaped gardens, built by Mr Berlusconi himself in the 1970s when he was a thrusting young property developer. With underground parking, a supermarket, bars and other facilities, it is one of the most fashionable addresses in the Milan hinterland. When he moved into television, Mr Berlusconi located the headquarters of Mediaset, his television company, here.

But in his declining years the estate has also become the headquarters of what is, in effect, his harem, it is alleged. Its presence was revealed by Corriere della Sera newspaper yesterday in yet another blow to the battered image of the Prime Minister as he prepares to defend himself against what could be the gravest crisis of his political career. Prosecutors in Milan are demanding that he be put on trial immediately for having sex with an underage prostitute.

The existence of the flats was revealed by Karima El Mahroug, a teenage belly-dancer from Morocco who trades under the name of Ruby Rubacuori, "Ruby heart-stealer". She ruined Mr Berlusconi's summer last year when it emerged that he had contrived to have her sprung from police custody after she was suspected of theft. He told police they were actually holding the granddaughter of President Mubarak of Egypt. As a prosecutor in Milan remarked subsequently: "If she's Mubarak's granddaughter, I'm Queen Nefertiti."

The dancer admitted to prosecutors that she had attended erotic evenings hosted by the Prime Minister at one of his homes. But now lawyers have taken advantage of the partial lifting of the Mr Berlusconi's immunity from prosecution to summon him for trial on a charge of having sex with the dancer when she was 17. Sex with a prostitute under 18 is punishable by up to three years in jail.

Mr Berlusconi does not deny hosting "relaxing parties" at his various grand homes, at which numerous young women, including showgirls, TV weather girls, escorts and prostitutes, were brought in to have dinner and listen to his jokes.

That those parties culminate in so-called "bunga-bunga" games, in which the women put on topless costumes and compete to see who can perform the hottest sex show, became known when Ms Mahroug blurted it out to prosecutors last summer.

Mr Berlusconi tried to stem the flood of revelations by having his lawyers round up other participants in the parties and get them to agree that none had had sex with him, and that the parties were innocuous. But three participants escaped their net, and it is their evidence that is crucially damaging for the PM.

According to one, a graduate in law and economy, the prize for the best bunga-bunga performer was to stay the night with Mr Berlusconi. All the other participants were sent off with gifts of €500 and upwards; the winner - the prosecutors claim to have chapter and verse on this, having tapped the phone of Mr Berlusconi's accountant - went home with €10,000.

Was Ms Mahroug a winner? Prosecutors claim, from studying phone records, that she was present at the villa a total of six times between February and April 2010. Circumstantial evidence that she was favoured by Mr Berlusconi is found in the amount of money that she splashed around last year. When stopped by police in September, she was found to have €5,000 in her bag - which she explained as having come from Lele Mora, the showbusiness agent whom prosecutors accuse of having procured prostitutes for Mr Berlusconi.

The circumstantial evidence may be strong, but did Mr Berlusconi have sex with Ms Mahroug? Both deny it, so how will the prosecutors go about proving it? According to La Repubblica, that is not as critical a detail as it may seem. The court has ruled that even if the sex act itself did not occur, what they charmingly term palpitazioni concupiscente - lustful petting - amounts to the same thing. And "bunga-bunga", as Ms Mahroug has explained, certainly involves that.

The woman who allocated the flats in Milano Due and who took care of practical details was said to be a former dental hygienist, Nicole Minetti, who became a regional councillor for Mr Berlusconi's "Freedom People" with his backing. The 14 young women are all aspiring television stars, hopeful that by making themselves available to the Prime Minister they would advance their careers.

Nobody expects Mr Berlusconi to be sent to prison in this case: his lawyers in the past have shown virtuoso skill in spinning out trials and appeals until they are killed by the statute of limitations. But what casts a new and dark shadow on Mr Berlusconi is the seediness of the charge, combined with the unprecedented confidence of the prosecutors.

With no clear successor to Mr Berlusconi, not even the opposition is eager for an election, but his majority is now minuscule. And the new case means he will have even more difficulty bolstering it: however strong his residual popularity with middle Italy, a leader on trial for underage sex is an unappetising ally.

Even people close to Mr Berlusconi admit the sex charge could be explosive. Michele Brambilla, a close Berlusconi ally, wrote in La Stampa yesterday: "Prosecutors ask for an immediate trial when they consider that their proof is evident and definitive, and that there is no need for further investigation or questioning."

If they are right and they do indeed have a "smoking gun", he concluded, "Berlusconi would be in trouble like never before".