Mikkel Kessler's camp has accused promoter Frank Warren of shielding Joe Calzaghe from a super-fight with his Danish super middleweight rival.
Kessler holds both the WBA and WBC belts at super middleweight
Calzaghe has the WBO title but Kessler holds both the WBA and WBC crowns.
Kessler's promoter Mogens Palle says that Warren, who is also negotiating for a fight against Jermain Taylor, has not stuck to an original offer.
"Warren's proposal was $5m, but when we met last week in London his offer had suddenly fallen to $3m," Palle said.
The Calzaghe camp has also offered $4m to Taylor, but the American WBC and WBO middleweight champion is holding out for at least $6m.
However, US television is thought to favour a domestic showdown with Kelly Pavlik, who impressed on the undercard of Taylor's lacklustre split-decision win over Cory Spinks last weekend.
That would leave Kessler as the other leading big-name for Calzaghe to next face, probably in September, although he is also interested in facing the winner of Bernard Hopkins' showdown with Winky Wright in January.
"Kessler is a good fighter. Frank has been talking to his promoter over the last few days, trying to do something with him," Calzaghe confirmed.
"But I think that fight may be six months or more down the road. Kessler is not a big name in America.
Mikkel Kessler cannot be compared to a bum like Jermain Taylor from the United States
"He's had a couple of good wins but in his last fight he beat Markus Beyer, who was shot.
"We can go down the Kessler road but Taylor is the one for me."
Palle says that he has offered Calzaghe a healthy pay-day to fight Kessler in Copenhagen, but that he was turned down flat by Warren.
"I said to him: 'Listen, to come here I offer you $5m net plus the British TV', but he said there is no way that Joe will come to Denmark," Palle told BBC Sport Wales.
"So I said that for the same terms we will come to the UK, because Mikkel Kessler doesn't mind where he fights Calzaghe - but we are far apart.
"Warren doesn't say 'net' and he doesn't say '$5m' in his offer."
Palle is adamant that Kessler, whose two belts hold equal weight in the boxing world with Calzaghe's WBO title, must be suitably rewarded if any fight takes place in the UK.
"If Calzaghe wants to fight in his backyard then this is something that Kessler has to be paid for, as he has the two most prestigious titles," Palle added.
"I don't give much for the WBO title, though Calzaghe has defended it 20 times.
"I can easily get Kessler to defend his titles 40 times! He can fight once a week and beat opponents like that.
"The chances of the fight happening in September are entirely up to Frank Warren because we are giving him the chance.
"He has tried everything else to avoid Kessler, for sure, we can prove that in black and white.
"Kessler cannot be compared to a bum like Taylor from the United States.
"That is not the first pathetic fight. I mean, everyone said it was a fantastic fight when Calzaghe fought Jeff Lacy, but Lacy was another pathetic fighter who couldn't fight.
"Why should Warren pay a guy like Taylor a lot more than Kessler who is 10 times better?"