Berlusconi is accused of paying to have sex with an underage Moroccan prostitute, Karima el-Mahroug, during alleged sex parties at his home.
Berlusconi and the woman deny having sex.
El-Mahroug said money she received from Berlusconi was given as part of a gift.
Prosecutors said the alleged prostitution ring was organized mainly by Nicole Minetti, a former Lombardy regional lawmaker and Berlusconi's former dental hygienist who is being tried in a different case. ANSA reported.
Prosecutors said retired television personality and Berlusconi friend Emilio Fede, along with bankrupt ex-talent scout Lele Mora, were involved in the ring. ANSA said they were being tried in a separate case.