Silvio Berlusconi Sex Trial: Italian Prime Minister's Secret Conversations Revealed

April 6, 2011— -- The trial of Italian Prime Minister Silvio Berlusconi, who stands accused of having sex with an underage prostitute and abusing his power to cover up the escapade, opened today in Milan as newly leaked wiretaps suggest he knew she was underage.

Prosecutors say 74-year-old Berlusconi paid to have sex with Moroccan night club dancer, "Ruby the Heartstealer" at least 13 times at his alleged "bunga bunga" parties or lavish orgies.

While Berlusconi has denied he had sex with Ruby, new wiretaps leaked to the media Tuesday suggest he knew Ruby was not of adult age.

In a phone conversation, Berlusconi reportedly said: "OK, what is important is that there are various people who can vouch for the fact that (Ruby) gave an age different to her real one. "Once that happens, there'll be nothing more to say. We just helped her because we took pity on her. Let's hope that it doesn't turn into a mess."

Ruby, whose real name is Karima El Mahroug, told a friend she was only 16 when she went to these parties. She turned 18 last November.

Today's brief hearing focused on formalities and the case was adjourned until May 31 when preliminary issues are expected to be discussed.

While the court still has to decide which witnesses to call, Italian Cabinet ministers and actor George Clooney may be asked to make an appearance.

Berlusconi sent a letter to the court today saying he could not attend because of "institutional duties."

Berlusconi was in Rome to discuss Libya in a ministerial meeting.

Bunga Bunga Parties

At the bunga bunga parties, TV showgirls, models and beauty queens, are said to have dressed up as police officers and nurses.

To thank them for attending, Berlusconi allegedly showered them with cash, jewelry, cars and paid for breast and lip surgery.

Ruby said Berlusconi told her, "I'll give you whatever amount you want…I'll cover you in gold, but the important thing is to keep everything under wraps."

Berlusconi is also accused of abusing his position when he asked police to release Ruby, after she picked up for allegedly stealing from a friend in May 2009.

If convicted on the charge related to underage prostitution, Berlusconi could face a prison term of six months to three years.

He could face four to 12 years if convicted on the abuse of office charge, according to the Associated Press.

ABC News' Phoebe Natanson and the Associated Press contributed to this report.