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ROME -- Italian Premier Silvio Berlusconi had sex with a significant number of prostitutes, Milan prosecutors alleged Monday in documents seeking authorization to search some of his properties.

The prosecutors are leading a probe aimed at determining if the 74-year-old media mogul paid for sex with a 17-year-old Moroccan girl who attended parties at one of his villas last year.

Prostitution isn't a crime in Italy, but exploiting or aiding prostitution with minors is.

The prosecutors allege that Berlusconi had sex with a "significant" number of young female prostitutes and used apartments to compensate the women, along with cash payments.

Berlusconi has denied wrongdoing.

The prosecutors asked the Chamber of Deputies to authorize a search of offices in a residential complex near Milan that belong to Berlusconi, who is both a member of the Chamber and premier.

Members of the Chamber enjoy parliamentary immunity including from arrest or searches in criminal probes, unless a Chamber committee decides otherwise on a case-by-case basis.

The teen, now 18, has said she was among a bevy of young women invited to parties at Berlusconi's Arcore villa near Milan. She has said in a TV interview that the premier last year gave her euro 7,000 ($9,000) to help her financially. She has said they did not have sex.

Prosecutors want police to search an apartment complex in Segrate, near Milan, which includes the offices they alleged could contain documentation that young women were given money and rent-free apartments -- in another residential complex -- by Berlusconi in compensation for prostitution.

In the request, Prosecutor Edmondo Bruti Liberati wrote that one of the premier's lawyers said the offices are part of Berlusconi's property and thus enjoy parliamentary immunity from searches.

Prosecutors alleged in their request that these parties were allegedly a cover for prostitution, and that besides the rent-free arrangement, cash payments doled out by a go-between compensated the prostitutes.

Liberati alleged that three close associates of the premier "continuously carried out an activity of inducing and abetting prostitution," by selecting and accompanying to Berlusconi's various residences, a "significant number of young women, who prostituted themselves with Silvio Berlusconi, receiving payment of money" from him.

Among the prostitutes, prosecutors alleged, was the 17-year-old. Liberati in his request to parliament said investigators' analysis of the girl's cell phone data indicated she "frequented" Berlusconi's Arcore residence in a period spanning February to May of last year.

The teenager has said she was first invited to Arcore for a soiree of dinner, song and dance with Berlusconi and several other young women on Valentine's Day in 2010. She claimed she had given her age as 24, so others at the party, including Berlusconi, wouldn't know she was a minor.

For three days running, culminating in a recorded video message shown on Italian TV Sunday night, Berlusconi has dismissed allegations that he paid for prostitutes, including a minor, as "grotesque."

He also claimed to have found a steady girlfriend following his separation from his second wife, Veronica Lario. Lario, who is divorcing him, has cited his frequenting of "minors" and "infatuation" with young women as a reason she wanted to end the marriage.

Italian news reports say prosecutors want to question Berlusconi later this week. The premier could invoke protection from prosecution in his role as premier. Italy's constitutional court recently ruled that judges could determine, instance by instance, if commitments connected to his role as head of government could excuse him from attending trial or appearing before prosecutors.

Among those associates prosecutors alleged helped procure the prostitutes are a young woman who is now a provincial government official from Berlusconi's party; a longtime executive in the premier's private TV empire, and a talent agent for entertainment programs.