Celtic will stand by Aleksandar Tonev, their on-loan Bulgarian forward, who has lost his appeal against a seven-match ban for racially abusing an opposition player.

The club expressed ''extreme disappointment'' yesterday over the decision to uphold a suspension on the player but it is not believed it will take the case any further, opting instead to approach the Scottish Football Association for talks to try to amend rules that did not demand corroboration over Aberdeen defender's Shay Logan's claim that Tonev called him a "black c***".

Logan reacted on Twitter by saying: "Do the crime, serve the time. Off ya pop geezer. #KickRacismOutOfFootball.'' He later posted: ''"On that note, let's forget what has happened in the past. It's done n dusted. Now time to move on and forget it. I'll always be me."

The SFA, in an unprecedented move, released the findings in full and it showed the reasons for upholding of the original verdict in October which was based on the belief that Logan was a more reliable and convincing witness than Tonev over what happened in the second half of a match in September at Celtic Park.

Celtic had challenged both the decision and the length of the suspension. Tonev's seven-match ban will be applied immediately, although one match has already been served by the player on loan from Aston Villa.

The club said in a statement: ''We do not consider that any player should be found guilty of such a grave offence on the basis of the evidence presented in this case. We would like to make it clear that at no stage was it ever suggested that Shay Logan had made any false allegations. However, Aleksandar Tonev's position consistently has been that he did not say the words that were alleged to have been said and that he is not a racist."

Celtic argued that the tribunal had failed to give Tonev a fair hearing, that it was entitled to reach its decision based on the facts and that the period of suspension imposed was excessive.

The tribunal had to adjudicate on the ''balance of probabilities'' and it found Logan a more convincing witness than Tonev, who was described as hesitant and guarded.

During the match, Logan complained to referee Bobby Madden that Tonev had made a racist remark towards him and also reported it to his captain, Mark Reynolds. He further reported the incident to his manager, Derek McInnes, as his team mates celebrated a goal.

Joe Di Paola, of the Celtic Trust, said: ''Like Celtic FC we have grave reservations about the process used by the SFA and the quality of justice which arises from it. Football players should be able to expect natural justice in terms of disciplinary processes relating to their employment and that does not seem to be the case here. Sadly, football players, like football fans, seem to be subjected to lower standards of justice than the rest of the population. ''

He added: ''Like Celtic FC we also abhor racism and our comments should not be seen as any defence of the words alleged to have been said.''

A spokesman for Show Racism the Red Card in Scotland said:"We are aware that the appeal may be taken further by Mr Tonev and cannot comment further on an on-going process.

"However, we will say more generally that football has to be a safe environment for players, other staff and spectators, where they are free of discriminatory behaviour.

"We also wish to point out that in the fight against racism, it is not particularly helpful to 'brand' individuals as 'racists', but to acknowledge that actions or language can be.''