Floyd Mayweather Jr. and Shantel Jackson
Floyd Mayweather Jr. and Shantel Jackson at the NBA game between Chicago Bulls and Los Angeles Clippers in Los Angeles December 30, 2011Reuters file

American boxer Floyd Mayweather Jr. has been hit with a new lawsuit by his ex-fiancee Shantel Jackson, with claims of physical and emotional abuse.

The 37-year-old has been accused of choking, blackmailing and imprisoning Jackson and also holding her at gunpoint, causing "pain and humiliation".

The couple, who met in 2006 and were in a relationship for seven years, broke up last year, ending a four-year engagement.

Jackson also alleged that Mayweather humiliated her by posting an image of an ultrasound scan online, claiming that they broke up because she aborted their twins, reports Daily Mail. The 29-year-old model also stated that the boxer threatened to share naked photos of her online, if she did not remove a picture with rapper Nelly from her social media accounts.

The development comes with Mayweather, who remains undefeated in the ring, set to fight Argentina's Marcos Maidana on 13 September in Las Vegas.

It has also been alleged that Mayweather subjected Jackson to physical torture and verbal abuse, including an incident where he held her at gunpoint and threatened to shoot her, and another in which he choked her and twisted her arm.

Mayweather has also been accused of imprisoning Jackson in his Las Vegas home and swearing at her, calling her a "b***h", and telling her "You're not sh*t without me. I made you who you are."

This is not the first incident where Mayweather has been accused of abusing his partner. The boxer, a repeat offender on the domestic violence front, was imprisoned for two months back in 2012, after being charged with acts of physical abuse against former lover Josie Harris.