Lewis, who appeared in Polanski's 1986 film Pirates, held a news conference on Friday, claiming the director took advantage of her "in the worst way" at his apartment in France when she was just a teenager.
The alleged incident came several years after Polanski fled the U.S. for France, skipping sentencing after pleading guilty to a charge of unlawful sex with 13-year-old Samantha Geimer in 1977.
Lewis, now 42, has given an interview to Britain's Mail on Sunday newspaper, alleging her encounter with Polanski in 1983 affected all her future relationships and ruined her Hollywood career as she sank into drug abuse the 1990s.
She tells the publication, "I know I should have gone to the relevant authorities at the time but I was scared and ashamed. I somehow thought it was my fault. He sexually abused me and manipulated me in the worst way. He has scarred me and the experience has definitely put a strain on my life. I was recently engaged to a lovely man, but I would often clam up physically and I don't think I am very good in relationships. I will never forgive Polanski for what he has done to me. I'll never know if my life would have been different if this had not happened. There needs to be some justice. I'm telling the truth and Roman Polanski knows I'm telling the truth."
And Lewis is fuming about the number of high-profile Hollywood stars who have come out in support of Polanski, adding, "I've been angry with some of the people in Hollywood who have spoken out in support of Polanski. Hollywood is giving the wrong message."
Lewis says she has met with Los Angeles County Deputy District Attorney David Walgren to report her allegations.
Polanski's lawyer Georges Kiejman has told French news channel i-Tele he is "absolutely astonished" by Lewis' claims, and reveals the director's legal team is considering taking action over the allegations, adding, "It is probable that we (will) take her to court".
Another of Polanski's attorneys, Herve Timime, adds, "Everything that has been said is a web of lies."