"When I was nine years old, I was raped by two of my uncles - my father's brothers," Karima El Mahgroug said in an interview on one of Berlusconi's TV channels.
"The only person who I dared to talk to about what happened, my mother, said - keep quiet, because if your dad finds out you're not a virgin, he'll kill you," said El Mahroug, who is more often known by her stagename Ruby.
After she was raped, she invented a 'parallel world' to shut out the horror. "I told my schoolmates I had a marvellous family, and I pretended I was Wonderwoman."
But her immigrant father was violent towards her and when she was 12, he threw a pan of boiling oil over her after she said she wanted to become a Catholic, El Mahroug claimed.
After that incident, El Mahroug said she first ran away from the family home in the eastern Sicilian coastal town of Letojanni, and stole a woman's handbag before being found by police.
But she denied she had become a prostitute. "I tried but I didn't succeed. Like my mother told me, you're born a hooker, you don't become one," El Mahroug claimed.
El Mahroug, who is now 18, also denied allegations that she had slept with Berlusconi when she was 17, in exchange for money and gifts.
"He never touched me, not even with a finger," she claimed.
Transcripts of tapped phone conversations published in Italian media on Wednesday quoted El Mahroug as saying she had being going to Berlusconi's home since she was sixteen.
Over 100 phone calls were recorded between them and a friend told investigators she had bragged they had sex, the reports said, citing the 385-page dossier detailing the investigation into the billionaire media mogul.
"I esteem him as a person and for helping me without anything in return," said El Mahroug, although she earlier told prosecutors Berlusconi had given her 7,000 euros, jewellery and an Audio car.
She also denied having asked the 74-year-old Italian premier for five million euros to keep quiet, as she had reportedly her ex-boyfriend's mother in an intercepted phone-call.
Also on Wednesday, a panel of the lower house of the Italian parliament said it would defer until next Tuesday at the earliest any decision on whether to allow Milan magistates to search the offices of Berlusconi's financial administrator Giuseppe Spinelli.
The prosecutors want to carry out the searches as part of a widening prostitution probe allegedly involving a number of other young women besides El Mahroug and three Berlusconi associates who are suspected of abetting prostitution.
Prosecutors say they have wiretap evidence that Spinelli paid young women, many of them aspiring showgirls, 5,000 euros each time they attended one of the premier's alleged sex parties at his villa in Arcore near Milan.
Berlusconi has refused calls from the opposition to resign over the case, dubbed Rubygate, in which he is also alleged to have abused his power in pressuring police to let Ruby out of custody after she was accused of theft.
"Are you mad?" the sex-scandal mired premier replied to reporters late on Tuesday.
He denies having sex with Ruby and other young women and said it would be "illogical" for him to appear before prosecutors to answer allegations that he used an underage prostitute.
Using underage prostitutes carries a jail term of up to three years in Italy while abuse of office can be punished by a term of up to 12 years.
Italy's president Giorgio Napolitano said on Tuesday the country was "in turmoil" over prostitution accusations against Berlusconi.
After a meeting with the premier, he urged "clarity" and said he hoped Berlusconi would respond to Milan prosecutors as soon as possible.
The Vatican has not commented on the case, but the Italian bishops have called the investigation a "devastating tornado" and their newspaper Avvenire said the implication of Italy's head of government in the probe was "hurtful and upsetting".
Berlusconi's centre-right government is senstive to losing Catholic support.