LONDON (AFP) - World football governing body Fifa on Monday announced disciplinary proceedings against West Ham United and Diafra Sakho over the striker's failure to play for Senegal at the Africa Cup of Nations.

He was ruled out of the tournament in Equatorial Guinea with a back injury, but came off the bench to score for West Ham in their FA Cup fourth-round win over Bristol City on Jan 25.

West Ham have maintained that they followed the correct procedures, but Sakho was left out of their squad for Saturday's 0-2 loss at Liverpool in the Premier League.

"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," Fifa said in a statement. "At this stage we can't make any further comments." If Fifa's case is proven, Sakho could face a domestic suspension and West Ham a fine.

Sakho travelled to West Ham's game against Bristol City by limousine, rather than by plane, in a bid to avoid aggravating his back injury.

West Ham manager Sam Allardyce confirmed that Sakho had been omitted from his squad for the Liverpool game due to the affair.

"With Sakho it is down to the situation we are in with Fifa," he said. "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."

Sakho, 25, joined West Ham from French side Metz last year and is the east London club's top scorer this season with 10 goals.