Anthony Joshua's representatives have had a "much-improved" offer for a world heavyweight title unification fight against WBC champion Deontay Wilder turned down, promoter Eddie Hearn has said.
Joshua (22-0, 21 KOs), who holds the WBA, IBF and WBO crowns, stopped Russian Alexander Povetkin at Wembley Stadium last month and is locked in to stage his next bout at the same venue in April next year.
Wilder (40-0, 39 KOs), who is scheduled to fight Tyson Fury in Los Angeles on Dec. 1, labelled Joshua a "coward" at a news conference on Monday for failing to secure a bout between them.
"It's frustrating. We keep requesting these meetings and they don't want them to take place, which is a bit strange when you're talking about the biggest fight in world boxing," Hearn told Sky Sports.
"We wrote to [Wilder's camp] after our fight with Povetkin and said we need to make our move soon because of mandatories in place for April 13, so could we have a meeting," Hearn added.
"They got back and said no, we're not interested in meeting you, make us an offer and we'll let you know.
"We went back and made a much-improved offer from the first one -- this one with a percentage split -- a very attractive offer and then requested a meeting, but they turned round and said 'no, we won't meet you.'
"We will probably have to move forward with a fight before Dec. 1, but we hoped that at least we could have a meeting so we can go face to face to discuss it."