A 20-year-old model from Montenegro Thursday said she was Italian Prime Minister Silvio Berlusconi's live-in girlfriend and backed his claims that he did not take part in raunchy parties at home. "I am Berlusconi's girlfriend and I live in Arcore," Katarina Knezevic told the Repubblica newspaper, referring to the 75-year-old premier's luxury villa, the scene of alleged debauched parties with call girls and would-be starlets. "We have been together since the Noemi affair, when he separated from his wife," she said. Veronica Lario filed for divorce on May 3, 2010, after revelations that Berlusconi had attended the 18th birthday party of a seductive blonde called Noemi, describing him as "a dragon to whom young virgins offer themselves. She also said she could ot stay with a man "who frequents minors." Knezevic said she met Berlusconi "in 2009, at the beginning of May, when I was 18. Silvio had just separated from his wife." Repubblica said her relationship with him began before her birthday on May 21, when she was still a minor. Should this be the case and if money or gifts changed hands, the beleaguered premier may face fresh legal problems. He is currently on trial for paying for sex in 2010 with a Moroccan pole-dancer known as Ruby, who was 17 at the time. "I am everywhere he goes. Wherever he is, I go too," Knezevic said. "Our relationship is not a mystery but until now we have avoided being photographed together," she said, adding that she did not consider the age difference to be a problem. "A person as extraordinary as him could be 100 years old, and he would have the same effect on me," she said. In wire-tappings carried out during the enquiry into the Ruby affair, several young women who attended Berlusconi's parties said they had seen Knezevic, who they described as "completely mad" and "put pressure on" the premier. "It's not true, I've never blackmailed Silvio, I don't even need to. All the girls are just jealous, they want to be in my place but as they've not managed it, they say all sorts of things about me and my family," Knezevic said. The model, who ran for the title of Miss Montenegro, is not the first to have claimed to be the premier's "official girlfriend." Her claims come shortly after the amorous confession of German actress Sabina Began -- known as the "Queen Bee" among the girls who attend the parties -- who said Berlusconi was the "only one to have made me feel like a woman." In January 2011, when the premier was first accused of having held orgies in his private villas, Berlusconi said he had been in a "a stable relationship" since splitting with his wife, with someone who "would never have allowed the absurd things reported in the newspapers to happen."