Los Angeles (AFP) - Floyd Mayweather has shot down rumours of a deal to fight martial arts star Conor McGregor, insisting he is content to remain retired.

The 39-year old American took to his social media Instagram account late on Tuesday, telling his fans that he wanted to set the record straight.

"There seems to be several rumours floating around media recently however, let the record show, there hasn't been any deals made in regards to a fight between myself and any other fighters. I am happily retired and enjoying life at this time. If any changes are to come, be sure that I will be the first to let the world to know."

His statement may be sincere or it may not be. He has been know in the past to often stretch the truth announcing several times that the fight of the moment would be his last only to use that ploy as a bargaining tool to try and sell more tickets.

The possibility of a fight between boxer Mayweather and McGregor appeared to get a boost as Ultimate Fighting Championship boss Dana White said he would pay US$25 million (S$35.57 million) to each.

White, president of the popular UFC mixed martial arts brand in which Ireland's McGregor stars, seemed to indicate in his comments on a Fox radio broadcast that the two would meet in a boxing ring, not the UFC octagon.

Mayweather, who retired in 2015 with a perfect 49-0 record, is considered one of the greatest fighters of all-time.

McGregor has never fought a professional boxing match. He became the first man to simultaneously hold UFC titles in two weight divisions when he beat Eddie Alvarez in New York on Nov 12.

At the end of November he was issued a California boxing license in a development that fuelled speculation about a showdown between the two.