A man who says he was Omar Mateen's lover has claimed the mass murderer acted out of revenge after finding out one of his partners was HIV positive.

Mateen, 29, shot dead 49 people at Pulse, a gay nightclub in Florida, on June 12 in America's worst mass shooting.

In an interview with Spanish-language television network Univision the man, who was identified only by the name Miguel, claimed he and Mateen were "friends with benefits".

He said their relationship started after they met on a gay dating website and lasted two months until December, during which time they met between 15 and 20 times at a hotel in Orlando.

Although Mateen pledged allegiance to Isil at the time of the attack, Miguel claimed that was not his motivation.

He said: "I’ve cried like you have no idea. But the thing that makes me want to tell the truth is that he didn’t do it for terrorism. In my opinion he did it for revenge."

He claimed Mateen had sex with two Puerto Rican men, one of whom he later discovered was HIV positive, and that he became "terrified".