Undefeated boxer Floyd Mayweather Jr is alleged to have once held a gun to his ex-fiancee's head during their tumultuous on-off eight-year relationship.

The five-division world champion has had a lawsuit filed against him by his former partner Shantel Jackson, who claimed in a press conference last week that he had beaten her.

It court documents released, Ms Jackson has claimed that the 37-year-old choked her, kept her a 'prisoner' in his Las Vegas home and once threatened to shoot her while at gunpoint, according to the Daily Mail.

The sportsman is also alleged to have stolen thousands of dollars worth of items from her and threatened to post online nude photos of her which he took while she was sleeping.

In the court papers, it states that Ms Jackson is seeking unspecified damages for battery, assault, defamation, invasion of privacy, false imprisonment, harassment and infliction of emotional distress.

Mayweather, who is accused of telling his former lover that he 'made her who she is', is facing a seven-day trial by jury in Los Angeles.