DUBLIN (REUTERS) - UFC (Ultimate Fighting Championship) lightweight champion Conor McGregor has apologised after being captured on video using a homophobic slur at the UFC Fight Night 118 event after his friend lost an mixed martial arts (MMA) bout.

McGregor, who lost a multi-million dollar boxing bout against Floyd Mayweather on Aug 26 after switching fighting codes, was filmed using the word "f*****" after his sparring partner Artem Lobov lost an unanimous decision to Andre Fili in Poland on Oct 21.

"I'm human, I slip up, I say stupid things every damn day. All I can (do) is hold my hand up and apologise if anyone was offended," McGregor, 29, told Reuters in an interview in his home town of Dublin.

"The word used to describe that opponent (Fili) was incorrect and very offensive, and I can apologise for that."