Baywatch star Pamela Anderson has alleged Tim Allen exposed his genitals to her on the set of his long-running American television sitcom Home Improvement.

In an excerpt from her January 31 memoir, Love, Pamela, the Playboy alumnus Anderson says she bumped into Allen on the first day of filming on set in 1991.

“On the first day of filming, I walked out of my dressing room, and Tim was in the hallway in his robe.

“He opened his robe and flashed me quickly – completely naked underneath,” reported Variety, which has obtained a copy of the book before its release next week.

“He said it was only fair, because he had seen me naked. Now we’re even.”

“I laughed uncomfortably,” she recounted.

Publisher Harper Collins claims Anderson’s book “breaks the mould of the celebrity memoir while taking back the tale that has been crafted about her”.

“[She] found herself tabloid fodder at the height of an era when paparazzi tactics were bent on capturing a celebrity’s most intimate, and sometimes weakest moments.”

At the time of the alleged incident, she was 23 years of age and appeared in the first two seasons of the show.

Allen, who won a best actor Golden Globe in 1995 for the show, was 37 at the time.

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In a statement to Variety, Allen, 69, said: “No, it never happened. I would never do such a thing.”

In a separate statement shared exclusively with Vanity Fair, Anderson expands on her account, insisting the incident took place.

“This true story is just one of many surreal and uncomfortable situations I learned to navigate,” Anderson writes.

“My book goes into how it made me feel over the course of my life and, in this case, my career.

“I have no ill will toward Tim. But like the rest, it should never have happened.”

In her memoir, Anderson says: “It was the first of many bizarre encounters where people felt they knew me enough to make absolute fools out of themselves.”

She notes, “’Here you go, Tim’, was my only line every episode, and when they decided to expand my part, it was, ‘Here you go, Tim. Have a nice day’.”

Anderson eventually left Home Improvement to focus on Baywatch, where she stayed from 1992 to 1997.

“I ended up making my career choice based on quality of life,” she writes.

An ‘accidental Cinderella story … on steroids’

Anderson is also headlining her Netflix documentary (produced by son Brandon Thomas Lee) which details other shocking details of her life from small-town Vancouver Island to Hollywood.

Ryan White, the director of Netflix’s Pamela, A Love Story (streaming January 31), tells the streaming giant’s fandom site he was given a first draft of her memoir before they started filming the documentary.

“Pamela had written it herself and it was really funny and fresh and the storyline was so sharp … you got this sense that she’s really just a small-town island girl [from Vancouver Island in Canada] who got caught up in a tornado for 30 years,” he said.

“She never sought any of this stuff out. It just fell in her lap.”

She spoke about the darkest moments of her life, allowed the team to read her diaries, and what she really thought of Disney+’s Pam and Tommy dramatisation about their infamous sex tape, saying it still gives her nightmares if she sees promotional material for the show.

According to yahoo.com.au, one of the first and most shocking revelations is her admission she attempted “to kill a babysitter when she was just a child to try and stop years of systematic abuse”.

“It was like three or four years of abuse,” she tells the camera.

“She always told me not to tell my parents. I tried to protect my brother from her. I tried to kill her – tried to stab her in the heart with a candy cane pen.”

On another occasion, she wrote in her diary she was raped by a 25-year-old man when she was 12.

She said she also wasn’t impressed by Hollywood veteran Sylvester Stallone, who offered her a “condo and a Porsche” to be his “No.1 girl” when she turned up in Hollywood.

Anderson has been married five times, and has two adult children, Brandon Lee and Dylan Jagger Lee.