Wilder e-mailed Hearn the offer for Joshua to fight him for the undisputed heavyweight championship in their next bout -- before the end of this year -- both sides told ESPN.

But despite admitting they would take the offer seriously, Hearn was adamant that a number of issues need to be ironed out before a deal can be agreed.

"They want total control of the show, date and venue of their choice. Not necessarily a deal breaker but if it is serious, we need to look at it, proof of funds, proper contract see the terms and what they require from us and we go from there," Hearn told IFL TV.

While Hearn stated that they wanted to make the fight in the UK, he would consider a substantial offer to take the fight elsewhere, but has little interest in agreeing a deal, with the fight put out to tender afterwards.

"No disrespect to Deontay Wilder but I don't believe he has that kind of money so I want to know where it is coming from and who is paying it. We can't just afford to accept a deal that doesn't exist. It is not a case of signing a deal and raising the money. If you have got is show it now and then we can talk."

The promoter questioned the timing of the offer, given the fact he has a meeting with Wilder's representatives on Friday and although acknowledging interest from Joshua, the British heavyweight also wanted to see the money and hinted it could be a mere PR stunt.

"He was like, who is putting the money up? Does the money exist? -- I cant answer that question at the moment. Where is it? -- I cant answer that question at the moment. When is it? -- I cant answer that question at the moment -- but the amount is of interest.

"As he said before, the 50-50 split is an interesting one but $50m is a lot of money. But it is not a case of we will agree a deal and then you have to go and find it. If it is there and up front, it is held and secure, it is definitely something we are going to look at."

Hearn ruled out an agreement before the weekend and cited Joshua's broadcast rights as a potential issue

"If there is a huge offer to do it in Vegas, we will definitely look at it. I am not interested in touting it out around the world to see who can pay the money; Saudi Arabia or Dubai for this fight. It has got to be the UK for this fight, or possibly Vegas.

"There are loads of things we need to know. Anthony has existing broadcasting agreements with certain broadcasters which he cant break. It is all great having complete control of the show but you obviously have to bear that in mind as well. At this stage I can't tell you if it is real or not but we have to take it seriously because if it is real, it is definitely of interest.

Hearn stated they have "prayed on the words of Anthony" who said previously he would fight Wilder for $50m, but he also revealed that Finkel has still not replied to the offer made to him two weeks ago.

"This is where it is clever. It is a 50-50 split against a guarantee of $50m. So if the fight made $120m he would get another $10m. But it is not going to make that. What they have done here is that they are banking on the fight could make $70m and he gets $20m against the $12.5 that we offered him.

He added: "Are they going to get the fight and put it out to tender. You either have the money or you haven't."