Shia LaBeouf
Shia LaBeouf at the Venice Film Festival in 2012Reuters

Hollywood star Shia LaBeouf has left fans stunned after declaring that he was whipped and raped by a woman he didn't know.

According to the 28-year-old actor, the attack occurred on Valentine's Day 2014, during his week-long #IAMSORRY performance art installation.

For five days earlier this year he invited members of the public to visit him one-on-one in a small room in a Los Angeles gallery where he sat wearing a paper bag over his face which read: "I'm not famous anymore."

Speaking to Dazed Digital, LaBeouf claimed that on the third day an unidentified woman sexually assaulted him while her partner stood in line outisde, as did LeBouef's girlfriend Mia Goth.

"One woman came with her boyfriend, who was outside the door when this happened," the Transformers star wrote in his email interview.

"[She] whipped my legs for 10 minutes and then stripped my clothing and proceeded to rape me.

"There were hundreds of people in line when she walked out with dishevelled hair and smudged lipstick. It was no good, not just for me but her man as well."

He went on to admit that the incident affected his relationship with his girlfriend of two years, Mia Goth.

"We were separated for five days, no communication. So it really hurt her as well, as I guess the news of it travelled through the line," LaBeouf wrote.

"When she came in she asked for an explanation, and I couldn't speak, so we both sat with this unexplained trauma silently. It was painful."

LaBeouf's bizarre admission caps off a year of headline-making antics.

In December he was forced to apologise for allegedly plagiarising the work of comic book writer Daniel Clowes saying he simply got "lost in the creative process".

"Copying isn't particularly creative work. Being inspired by someone else's idea to produce something new and different IS creative work," he told his 70,000 twitter followers.

He also courted global attention in February when he arrived at a Berlin premiere for his film Nymphomaniac with a paper bag over his head also inscribed with the words "I Am Not Famous Anymore".

Last month, the Jewish-born former child star revealed he had converted to Christianity after he "found God" while working on his new film Fury.