London - Britain's world heavyweight champion Anthony Joshua has been given a 24-hour deadline to agree a fight with Russia's Alexander Povetkin or risk being stripped of one of his titles.

Joshua added the World Boxing Organisation heavyweight belt to the World Boxing Association and International Boxing Federation straps he already held when he beat New Zealand's Joseph Parker in Cardiff in March.

Since then Joshua's promoter, Eddie Hearn, has been trying to set up a unification bout with World Boxing Association heavyweight champion Deontay Wilder, but has not yet managed to do a deal with the American's camp.

But the WBA are tired of waiting and have now told Joshua he must fight Povetkin, their mandatory challenger.

WBA president Gilberto Mendoza, in a statement issued Tuesday, said: "Today the WBA requested an answer from Anthony Joshua's team regarding his fight with the mandatory challenger Alexander Povetkin.

"The WBA have allowed over a month extension to negotiations with Povetkin and also ongoing discussions with Deontay Wilder.

"It appears the Wilder team have not returned the contract for the fight and therefore we are requesting a date for the Joshua versus Povetkin fight with immediate effect."

Given talks with Wilder appear to be stalled while his management seek "clarification" over the terms of a fight contract, a contest with Povetkin may well represent the 'next best bout' for London 2012 Olympic champion Joshua, who is unbeaten as a professional.

Joshua, 28, won his first world title in 2016 and has made five defences, taking his record to 21-0 with 20 knockouts.

Wilder, 32, improved to 40-0 with 39 knockouts when he knocked out previously unbeaten Cuban Luis Ortiz in the tenth round in Brooklyn, New York, on March 3.

Povetkin demonstrated his considerable punching power with a fearsome knockout of Britain's David Price on the undercard of Joshua's win over Parker at Cardiff's Principality Stadium.

Best known for staging Wales rugby union internationals, the Principality - which has a capacity of over 73 000 - could also play host to a Joshua-Povetkin clash.

Were that fight to take place later this year, it would likely mean any bout between Joshua and Wilder would be delayed until 2019 at the earliest.