West Ham United have attempted to placate Senegal via an intermediary as they grow increasingly concerned about the possible ramifications of the Diafra Sakho row which could, according to Fifa’s rules, extend to them being kicked out of the FA Cup.

The London club selected Sakho for their fourth-round win at Bristol City on 25 January – the striker came on as a 57th-minute substitute to score the only goal – even though they had declared him unavailable because of injury to play for Senegal in the Africa Cup of Nations, which is still ongoing in Equatorial Guinea.

Senegal, who would exit the tournament on 27 January after a 2-0 defeat by Algeria in their final group fixture, were fuming and they complained to Fifa which, in turn, began an investigation. The governing body’s regulations say that players cannot appear for their clubs during the period that they should have been released unless there is a prior agreement between all parties. There was no agreement between West Ham and the Senegalese Football Federation.

The relevant Fifa rule reads: “If a club refuses to release a player or neglects to do so despite the provisions of this annexe, the Fifa Players’ Status Committee shall furthermore request the association to which the club belongs to declare any match(es) in which the player took part to have been lost by the club concerned.”

West Ham maintain that they have done nothing wrong and they have called for the proceedings to be dropped. They say that Sakho could not participate at the Nations Cup because his back injury made it impossible for him to get on an aeroplane. They got him to Bristol for the Cup tie in a limousine.

Senegal regard West Ham’s behaviour as arrogant and insulting. How, they wonder, could Sakho have been OK to sit in a car for a round-trip that would have added up to more than six hours and take part in a Cup tie? It has also been noted at the Senegalese Federation that West Ham pulled Sakho out of last Saturday’s 2-0 Premier League defeat at Liverpool after they had been made aware of the Fifa investigation.

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.”

West Ham were furious last November when Sakho returned from international duty with pain in his back – the result, according the manager, Sam Allardyce, of a medical “mishap” from the Senegal staff. West Ham duly opened legal conversations with the Senegalese Federation. When Sakho re-aggravated the injury in his club’s 1-1 draw at West Bromwich Albion on New Year’s Day, it was the trigger for him to be stood down from the Nations Cup.

But West Ham now feel sufficiently worried to have engaged an intermediary to attempt to smooth the waters with Senegal. The trouble is that he has not got very far. Senegal’s anger remains intense.

The Football Association regards this as a Fifa matter and it would be surprised if the body insisted on West Ham being expelled from the FA Cup. There is also the issue of the potential time-frame of such a punishment; West Ham are scheduled to go to West Bromwich Albion in the fifth round on Saturday week. It stands to be a minefield and an expulsion would represent the most draconian application of the regulations.