A swirl of intrigue has surrounded Mascherano and Tevez' shock move to Upton Park, with speculation raging that the South American duo are merely being placed in the shop window before being sold to a bigger club next year.

Though the deal has been described as "permanent" by West Ham, no other details about the transfer from Brazilian club Corinthians have been divulged.

Reports have said the two players would have been valued at between 40-60 million pounds in an open transfer market -- money that West Ham plainly does not have.

The deal is believed to be part of a takeover bid of the Hammers by British-born Iranian businessman Kia Joorabchian, whose company Media Sports Investment (MSI) owned the two players.

Yet the lack of transparency surrounding the deal has has caused concern at European football's governing body UEFA.

"This is certainly a strange deal and it is worrisome because it is part of this evolution of football in which money always plays an increasing role and more traditional values such as loyalty or regional roots or liking for a club seem to be very old fashioned," a UEFA spokesman said.

"We feel the same as the supporters. Football is more than a business. It is something completely different, it involves loyalties, emotions, fidelity. "These are two exciting players but, at the same time, this was the jersey of Bobby Moore and Geoff Hurst - people who spent their lives at the club. "Maybe these players will be at West Ham 10 years from now. If so, that is great. But, at the same time, one cannot help but have some doubts."

Sources close to Joorabchian meanwhile denied that Tevez and Mascherano would be sold on to a bigger club next year.

"It is preposterous to say they have just come here to be put in the shop window," a source close to Joorabchian was quoted by the Press Association news agency as saying.

"There are no plans at all for them to move. This is the best place for them to be and show their talent to the full extent. It is good for West Ham.

"They are obviously not going to play in a team that is struggling against relegation but, if it all goes well, they will stay at West Ham."

West Ham confirmed in a statement to the London Stock Exchange Friday that they had held talks with Joorabchian and MSI over a potential takeover bid.

Joorabchian has been repeatedly linked to various Russian tycoons, including Chelsea's billionaire backer Roman Abramovich. Joorabchian has denied any link to Abramovich.