"There is no doubt that Karima El Mahroug (Ruby) had sex with Berlusconi and received the benefits of it. He knew that the girl was under 18," prosecutor Ilda Boccassini said.
According to prosecutors, Berlusconi paid for sex with then 17-year-old el-Mahroug, a Moroccan belly dancer, at his vast mansion near Milan in 2010 when he was prime minister.
Berlusconi is on trial for having sex with an underage prostitute and for allegedly pressuring police to release el-Mahroug. In Italy, the age of consent is 14, but paying a woman under the age of 18 for sex is a criminal offence.
Berlusconi is also charged with abuse of office for getting el-Mahroug released from custody for an unrelated petty theft offence in order to cover up their liaison.
Ruby denies having sexual relations with ex PM and claims that the money she received from him was simply a gift. Prosecutors have urged a Milan court to hand a six-year prison sentence and life ban from office to Silvio Berlusconi for having sex with a minor and for abuse of power.
Berlusconi faces up to three years in prison for the sex charge and up to 12 years for allegedly pressuring police to release el-Mahroug. Prosecutor Ilda Boccassini asked the court to give Berlusconi five years in jail for corruption and one year for paying an underage prostitute for sex.
"Several witnesses in the case were forced to lie," she told the court, a claim that Berlusconi's lawyer Piero Longo disputed.
The defence will start arguing its case June 3 and a sentence is expected June 24, judicial sources said.
With inputs from IANS.