The latest allegation involves a woman in her 20s who was attacked in a car parked outside a Dublin pub last week, according to The New York Times, which cited people who spoke on condition of anonymity because of Irish laws surrounding investigations.
McGregor, 31, has not been charged, and the police have yet to interview him about the allegation.
The fighter was already under investigation for a separate case involving a woman who was attacked at a hotel where McGregor stayed in December. The findings of the investigation were sent to Ireland’s prosecutor’s office earlier this year, and McGregor is waiting to learn whether he will be charged in the case.
“Conor McGregor is frequently the subject of rumors,” a publicist for the brawler told The Times in an emailed statement. “He emphatically denies any report accusing him of sexual assault.”
McGregor announced his retirement on Twitter in March, hours before the allegations about the hotel assault became widely known.
On Thursday, McGregor known as “The Notorious” challenged New Jersey fighter Frankie Edgar to a match later this year.
Dublin-born McGregor, one of the world’s highest-paid sports stars, has been involved in a series of police cases.
Earlier this month, he was charged with assault for punching an elderly man at a Dublin pub, a moment that resulted in a viral video.
He settled a case earlier this year over accusations he grabbed and smashed the phone of someone who was filming him outside a Miami hotel. Last year, he dodged jail time after he threw a metal hand truck at a bus outside the Barclays Center in Brooklyn following a press conference.