Milan prosecutors were investigating whether Berlusconi paid for sex with an underage girl from Morocco and then abused his power in trying to cover up the encounters.
Berlusconi has criticized the probe, calling the allegations "incredible and grotesque."
The teenager, a nightclub dancer nicknamed Ruby, said Saturday in an interview on Sky TG24 TV that Berlusconi didn't know she was a minor when she was invited to his villa near Milan last year "because I told everyone I was 24," not 17.
Asked why Berlusconi gave her the money at the first of several evening parties she said she attended at one of his villas outside Milan, Ruby replied, "because I had just arrived in Milan and he knew of my difficult family situation" and wanted to help.
As in other interviews Ruby has given, she reiterated that there was "absolutely no" sex between them.
Ruby, now 18, said that guests dined and danced at the parties and that Berlusconi "sang and told jokes."
Prosecutors say they are investigating whether the premier had sex with the then-17-year-old girl and then used the powers of his office to try to cover up the encounter. Prosecutors issued a summons Friday for Berlusconi and his lawyers to appear for questioning.
Berlusconi has been engulfed in several scandals stemming from his private life, including reports of wild parties at his mansions and alleged encounters with prostitutes. In one case, Patrizia D'Addario, a self-described call girl, said she spent the night with Berlusconi when Barack Obama was elected U.S president. She later gave purported tapes of her encounter with Berlusconi to an Italian magazine.
In 2009, his second wife, Veronica Lario, announced she was divorcing him, citing Berlusconi's purported fondness for younger women. Berlusconi has made no apologies for his lifestyle, but has denied ever paying to have sex.