West Ham have called for FIFA's "unfounded" disciplinary case against them and Diafra Sakho for a "potential violation" of regulations over the striker playing for his club during Senegal's African Nations Cup campaign to be thrown out.

The world governing body on Monday confirmed proceedings had been opened following a complaint by the Senegal national association after Sakho came off the bench to score the only goal in West Ham's FA Cup fourth-round victory over Bristol City on January 25, despite having been ruled out of international duty with a back injury.

The Barclays Premier League club maintain correct procedures were followed, with Senegal kept fully informed at every stage of the player's treatment, but in the wake of the dispute subsequently decided to leave Sakho out of the squad for Saturday's match at Liverpool, which they lost 2-0.

A statement from West Ham said: "Diafra Sakho and West Ham United vigorously deny that they have acted in breach of FIFA regulations. They regard the proceedings as clearly unfounded and are requesting their dismissal. At this stage, neither the player nor the club can make any further comments."

Hammers manager Sam Allardyce had defended the decision to play Sakho at Ashton Gate, the forward having been driven down from London owing to medical advice barring him from travelling by plane.

However, the club later decided not to select him for the Premier League match at Anfield.

Speaking on Saturday, Allardyce confirmed: "With Sakho it is down to the situation we are in with FIFA. While it is happening it is not conducive for us to be putting him on the field until it is resolved sadly.

"If you speak to the lad you would know how angry and disappointed he is at being denied the opportunity to play football when it is not our fault.

"We have covered all the rules and regulations, but at this moment in time it is sensible to do the right thing and not get involved any more."

Senegal crashed out at the group stage of the tournament in Equatorial Guinea.

Should the case be proven then Sakho could face a domestic suspension and West Ham a fine from the world's governing body.

It has also been suggested West Ham could face a compensation claim from Bristol City if FIFA rule they fielded a player who should have been ineligible.

A FIFA statement on Monday morning said: "We can confirm, that disciplinary proceedings were initiated against the player Diafra Sakho (SEN) and the club West Ham United for a potential violation of the FIFA Regulations on the Status and Transfer of Players.

"At this stage we can't make any further comments."

Midfielder Cheikhou Kouyate did play for Senegal, but has returned to east London now carrying an ankle injury.

James Collins, Winston Reid and Andy Carroll all suffered knocks against Liverpool and will be assessed ahead of Sunday's home match against Manchester United.