Anthony Joshua and Tyson Fury could have to pay Oleksandr Usyk £1.5 million each if they want to make their fight for all four world heavyweight titles.

Usyk is currently the mandatory challenger to Joshua's WBO strap and is the major stumbling block in the way of the two Brits competing to become the first undisputed champion since Lennox Lewis.

But AJ's promoter Hearn has warned Usyk they may decide to vacate the WBO belt if it becomes too expensive to keep.

He told Sky Sports: "Imagine my conversation with Fury and Joshua: 'To keep all the belts on the line you've got to pay three per cent to the governing bodies (which equals) £1.5m you both individually have to pay plus Usyk wants a couple of million'. They would say: 'What?'.

"This fight is bigger than the belts. This is undisputed. AJ wants to be the undisputed champion but isn't this fight even bigger than that? Isn't this fight the answer to all of our questions? Who is the best? Who is the baddest man on the planet? Who is the best heavyweight?

"At some point we have to take charge of the sport and say: 'No more'.

"But first I will do everything that I can to keep the belts on the line. For me, that is the glory - seeing AJ covered in every bit of silverware. That has always been his aim.

"Once they've fought for the undisputed championship, if the belts become fragmented then so be it. But I'd just love that moment."

If Joshua does vacate the title, Usyk could fight fellow Brit Joe Joyce for the title after his victory over Daniel Dubois in November.

Fury's promoter Bob Arum confirmed on Thursday that a location has been agreed to stage the fight later this year.

However, he also said a date has not yet been finalised.