Tevez (right) and Mascherano were surprise signings for the Hammers

Reports claim the Hammers are contractually obliged to start with the pair, who signed from Brazilian club Corinthians last week, if they are fit.

"That is categorically untrue," Hammers spokesman Phil Hall told BBC Sport.

"And it is completely manager Alan Pardew's shout as to whether he picks these two players."

Businessman Kia Joorabchian, who engineered the transfers of both players from Corinthians, was quoted in the Guardian as saying: "There is no clause for them to play or not to play.

"That is totally the manager's choice. If Alan doesn't think they are good enough to play any game, or for tactical reasons, then that is his choice."

West Ham's capture of two of the hottest properties in South American football last Thursday led to some raised eyebrows.

Few details about the transfer are known but there have been rumours that the players' stay at Upton Park may be a short one, with suggestions that the Hammers were a 'surrogate' club.

Reports claim that Tevez and Mascherano were offered to Chelsea, Arsenal, Sevilla and Roma but they baulked at the asking price.

Portsmouth were also said to have been given the opportunity of a similar deal to West Ham but declined.

It was also revealed on Sunday that Manchester United had been offered the pair but were not interested.