Mel Gibson allegedly cheated on ex-girlfriend OKSANA GRIGORIEVA while she was pregnant with their daughter.

Porn producer Violet Kowal claims to have had a three-month fling with the 'Mad Max' star last year, with the reported romps happening at his Malibu home and office in Santa Monica.

The 26-year-old Polish filmmaker told National Enquirer magazine: "Mel's break-up with Oksana doesn't surprise me at all. Clearly, Mel can't commit to just one woman."

Violet was also very impressed with 54-year-old Mel's skills in the bedroom department, saying: "Mel's great in bed! It was the best sex I've ever had!"

Although Mel's lawyer has branded the story "an absurd fabrication", Violet is said to have passed a lie detector test.

Oksana gave birth to Lucia last November but she and Mel announced their split just five months later.

While she has refused to give the real reasons behind the break-up, the Russian musician has previously hinted there would be some shocking revelations.

She said: "I can tell you that we have split up, suddenly and recently. Unfortunately, I cannot give you the reason. But you will find out everything quite soon.

"Here is the official version - we split up by mutual consent and we will raise our daughter together. She is currently with my mother in my Los Angeles home."

Despite initial reports insisting they are still on good terms, it was recently claimed Mel ended their relationship following a huge row after Oksana accused him of cheating.

Mel has seven children with estranged wife Robyn, who filed for divorce last May.

Following the legal proceedings, it emerged the couple had been separated for some time and the actor was in a relationship with Oksana, who has 12-year-old son Alexander with ex-boyfriend Timothy Dalton.