Manchester United were last night accused of "double-dealing" after pulling the plug on a world record £70m sponsorship deal.
The claim came from David Kinsman, chief negotiator of betting and casino company Mansion.
Mansion had been discussing a potential four-year deal to sponsor United's shirts, but they claim the club have been in secret talks with another company.
United have hit back, saying: "We have not and do not enter into periods of exclusive negotiation."
Kinsman said that at the request of United commercial director Andy Anson, he cut short business meetings in the Far East and flew into London on Friday, reportedly believing negotiations were about to be concluded.
Mansion say that having been assured on Saturday there were no problems with discussions, Kinsman then took a call from Anson on Sunday night in which the United official said he had also been talking to another unnamed company and contact with Mansion was being terminated. Kinsman and his executives were said to be stunned.
Kinsman said: "We are not naive businessmen by any stretch of the imagination but this has left us flabbergasted. This might be the way Manchester United do business, but it does not suit us.
"It was indicated to us that we had done a deal and I flew in from
"It was something of a surprise, therefore, to be told that United had been negotiating with someone else. During the negotiating process we had no idea this kind of double dealing was going on."
Given the figures Mansion are talking about, it appears purely in financial terms United will not lose out following Vodafone's decision to terminate their £9m-a-year deal two years early. Mansion are not the first company to express their concerns about the club's negotiating policy.
United said in a statement: "We would understand why anybody would be disappointed at not securing the shirt sponsorship deal for Manchester United.
"We have not and do not enter into periods of exclusive negotiation and every party we have discussed the shirt sponsorship with are aware of that.
"All the parties were aware that several discussions were going on at the same time and our priority is to look for the most appropriate deal for Manchester United.
"It's only the third time we have sold this property and clearly we want to get it right.
"We have been having discussions with Mansion, and we are sorry they feel that way and wish them every success in the future."