The actor Harry Dreyfuss, son of Richard Dreyfuss, has claimed that Kevin Spacey groped him aged 18.
In the account published on BuzzFeed, the son of the Jaws actor revealed how Spacey groped him in 2008, while his father was in the room.
Dreyfuss said that after seeing other allegations about the House of Cards actor, he decided to speak out.
Dreyfuss wrote in a piece for BuzzFeed: "It happened one night when the three of us were alone in Kevin's apartment rehearsing my father's lines. My father didn't see, and I didn't tell him about the incident for many years. Instead, I spent the next nine years telling people the story at parties for laughs."
He accused Spacey of being a "sexual predator" but had "never thought talking about it seriously."
Detailing the account which took place during a script-reading session, Dreyfuss said: "Over the course of about 20 seconds, centimetre by centimetre, Kevin crawled his hand from my thigh over toward my crotch. My mind went blank. Suddenly, he had completed his journey and now he had all of me in his hand. I stopped reading the script and my eyes went wide."
Taken aback by the incident, Dreyfuss, now 27, explained how he had lost track of time and was unsure if it lasted 20 seconds or even five minutes.
When asked to comment on Dreyfuss's story, Bryan Freedman, a lawyer representing Spacey, said, "Let me be clear, Mr. Spacey absolutely denies the allegations."
Harry Dreyfuss concluded his article by saying he hoped that his story could "serve as inspiration to others who may have felt that they couldn't or shouldn't speak up until now".
Numerous allegations have been revealed after Star Trek actor Anthony Rapp's initial claim that, as a 14-year-old, Spacey had attempted to "seduce" him.
Spacey has said that he was "beyond horrified" to hear about the incident which he couldn't recall, and has since started treatment.
The claims have resulted in Spacey being axed from the hit series House of Cards, as well as the launch of a police investigation in the UK.