UFC president Dana White has told Conor McGregor he has to fight Dustin Poirier at lightweight if their bout is to go ahead in January.

McGregor and Poirier agreed to a clash on January 14 via social media, although it has not yet been confirmed through official channels.

But White remains confident the Irishman will not go back on his word as he prepares for his first outing in 12 months.

Speaking to BT Sport, he said: "The deals not signed yet but in the history of dealing with Conor McGregor, Conor McGregor has never come out publicly and said ‘I accept this fight’ and then not fought and turned down a fight. I expect the fight to go on."

However, White was also very insistent that the bout must happen at 155 pounds as it has no meaning up at 170.

"I'm not putting on a friggin' multi-million at a catchweight that means nothing," he added.

"The fight means nothing at 170. Neither one of those two are ranked at 170 pounds and it doesn't do anything in the '55 division if either one of them win 'cos they're fighting at 170. It literally makes no sense.

"There are plenty of organisations that put on fights that make no sense. You can go and watch those fights every weekend. That's not what we do here."

McGregor’s last fight against Donald ‘Cowboy’ Cerrone was at 170lbs and he destroyed him in just 40 seconds.

But the Irish superstar has fought at lightweight in the past against the likes of Eddie Alvarez and Khabib Nurmagomedov.