Anthony Joshua wants to “see the money” before agreeing to Deontay Wilder’s $50m (£35.9m) unification fight offer, says promoter Eddie Hearn.
American heavyweight Wilder posted a video on Twitter showing WBO, IBF and WBA titles holder Joshua, 28, saying he would accept the fight for $50m.
But Hearn said he must be convinced the money “exists” before agreeing to the bout “in either London or Vegas”.
Finkel also said the offer contains no rematch clause and that it would be the next fight for each boxer, taking place between September and December at a venue of Wilder’s choosing.
Hearn said earlier this month that the WBA has ordered the Briton to enter into negotiations with mandatory challenger Alexander Povetkin.
Unbeaten Joshua added the WBO belt to his collection after a unanimous points win over Joseph Parker in Cardiff on 1 April, while Wilder beat Luis Ortiz in his last fight in March.