Demi Moore has said she was raped at the age of 15 in her home, by a man who claimed to have paid her mother $500.

The Hollywood star, 56, made the allegation during a candid interview on Good Morning America to discuss her memoir, Inside Out.

Speaking to Diane Sawyer, she said she came home to find the older man, who knew her mother, in her apartment.

After he had raped her, Moore alleges he said her mother had sold her to him. In the book, she writes: “It was rape. And a devastating betrayal, revealed by the man’s cruel question: how does it feel to be whored by your mother for $500?”

Moore’s mother was an alcoholic who, according to Moore, took her to bars when she was a teenager so that men would notice them. She died in 1998.

Asked if she believed the man, she said: “I think, in my deep heart no. I don’t think it was a straightforward transaction. But she still did give him the access, and put me in harm’s way.”

Moore was one of the most successful actresses of the 1990s thanks to starring roles in films including Ghost, A Few Good Men and Indecent Proposal. She dedicated her book to her mother, as well as her three daughters with ex-husband Bruce Willis.

Moore said her mother’s first attempted suicide occurred when the actress was 12 – and it was her intervention that saved her mother’s life.

“I remember using my fingers, the small fingers of a child, to dig the pills my mother had tried to swallow, out of her mouth,” Moore writes in the book.

She told Sawyer it happened “many, many times” after that. “[My childhood] was done. Life-changing moment.”

In the book, Moore writes of her prior battles with substance abuse; she went to rehab for drug and alcohol addiction in the mid-1980s. On Good Morning America, she discussed how her life began to unravel again around 2012, when her marriage to Ashton Kutcher broke down, her children stopped speaking to her and she weighed 102 pounds. She collapsed at a party and was hospitalised after smoking synthetic cannabis and inhaling nitrous oxide, according to the New York Times.

“I guess the fundamental question that came forward for me was, how did I get here?” she told Sawyer. “I blinded myself, and I lost myself.”

Moore found fame in the 1980s with appearances in films such as Blame It On Rio and St Elmo’s Fire, before her starring role in 1990 romantic thriller Ghost, opposite the late Patrick Swayze, cemented her status as one of the world’s biggest stars.

After becoming the highest paid actress in Hollywood critics gave her the nickname “Gimme Moore”, but Moore was not bothered by the jibe.

“Why shouldn’t all women be paid equal to the quality of the work they’re doing? Just treat me the same. No better, no worse,” she said.

PA contributed to this report

• In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found atwww.befrienders.org.