A friend of the late Haim, Dominick Brascia, came forward with the story to The National Enquirer on Wednesday. The assault allegedly occurred during the filming of the 1986 film, Lucas.
"Charlie Sheen categorically denies these allegations," Sheen's representative told The Hollywood Reporter.
Brascia claimed Haim told him about the incident, which involved Sheen sodomizing the child actor.
"Haim told me he had sex with Sheen when they filmed Lucas," Brascia claimed. "He told me they smoked pot and had sex. He said they had anal sex. Haim said after it happened Sheen became very cold and rejected him. When Corey wanted to fool around again, Charlie was not interested."
The account was previously alluded to in Corey Feldman's book,Coreyography: A Memoir. Feldman and Haim were known to be best friends throughout their careers.
"At some point during the filming [of Lucas], [Haim] explained an adult male convinced him it was perfectly normal for older men and younger boys in the business to have sexual relations, that it was 'what all guys do,' " Feldman wrote. "So they walked off to a secluded area between two trailers during a lunch break for the cast and crew. And Haim, innocent and ambitious as he was, allowed himself to be sodomized."
Feldman had not named Sheen in his account and has not spoken up about Brascia's claims.