Reports over the weekend suggested a deal between the English Premier League giants and the Gibraltar-based firm was imminent.
But gambling outfit Mansion pulled the plug on any proposed deal after the club confirmed it was still in talks with another potential partner.
In a statement, Mansion said: “Discussions with Manchester United worth between £65m and £70m over four years, have been terminated. Mansion's offer would have been a significant deal for Manchester United.”
Mansion negotiators are reported to be ‘furious’ at the way United have handled the negotiations – echoing sentiments from electronics firm LG who expressed anger at the way they were played off against other brands.
Mansion COO David Kinsman has said a verbal deal had been reached between the two parties before the third party’s involvement was revealed.
Kinsman is reported to have 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 something of a surprise to be told United had been negotiating with someone else.
“During the negotiating process we had no idea this kind of double dealing was going on.”
Mansion say they are now looking at other Premiership clubs.
