Manchester United's attempts to sign Athletic Bilbao midfielder Ander Herrera turned into farce after leading football journalist Guillem Balague claimed the delegation which went to Spain to negotiate the transfer were in fact imposters.

Earlier today, reports suggested that a three-man delegation from Old Trafford had travelled to Spain to pay Herrera's buy-out clause in person, after Herrera agreed to move to Old Trafford.

However Spanish journalist Balague, speaking to Sky Sports News, said the putative delegates didn't even represent United at all.

Balague reported: "Representatives of Manchester United went to the Spanish league about 7.30, saying they were willing to pay the buy-out. Even though they were in the building for an hour, they left without paying the buy-out clause.

"It seems the delegation might not even have been from Manchester United."

Balague suggested the 'imposters' may have been unwanted intermediaries trying to make money by acting as middle-men, but didn't divulge further details.

The report was apparently corroborated by Balague's fellow reporter Andy West, an expert on the Spanish league, who wrote: "Apparently a group of men claiming to be United representatives spent an hour at the La Liga offices in Madrid today, but it turns out they had nothing to do with the club and were presumably just attempting to get a cut of the deal in an elaborate fraud.

"Must be stressed these are just rumours but the Spanish media have published pictures of men in black suits - supposedly the United "representatives" - coming out of the league offices carrying briefcases.

"All very strange and no doubt the truth will come out in the next few days."

The news is likely to bring further condemnation for United's new chief executive Edward Woodward, who has been frequently criticised for his attempts to augment the club's squad this summer.

United have been castigated for refusing to meet Thiago Alcantara's buy-out clause earlier in the transfer window, and for lodging bids for Cesc Fabregas and Daniele De Rossi which fell far beneath the players' true market values.

Critics have also suggested United have left their summer transfer business far too late, with reports of bids for De Rossi and Herrera only emerging in the last few days of the window.

Although United appear likely to sign midfielder Marouane Fellaini from Everton, the transfer is unlikely to appease fans angry at what they perceive to be an amateurish approach to signings this summer.

United insist the deal broke down because they felt Herrera's buyout fee was the wrong valuation and they were unable to bring it down.