Celtic winger Aleksandar Tonev was hit with an SFA notice of complaint on Friday night after becoming embroiled in a race row with Aberdeen defender Shay Logan.

Summoned to a principal hearing on October 9, the loan signing from Aston Villa has been accused by Logan of calling him a ‘black c***’ during last weekend’s 2-1 victory for the Scottish champions at Parkhead.

And it’s understood the governing body are prepared to hammer the Bulgarian on the ‘balance of probability’ - even if there are no witnesses or audio evidence of the alleged remark.

Aleksandar Tonev is accused of using 'insulting and abusive language of a racist nature' towards Shay Logan

Tonev carries the ball forward for Celtic as Logan (right) gives chase during Saturday's match

Compliance officer Vincent Lunny wrote to both clubs to gather information earlier this week. And now Tonev has been charged formally with ‘excessive misconduct by the use of offensive, insulting and abusive language of a racist nature’ after the SFA decided the 24-year-old has a case to answer.

The wide man vehemently denies the claims and has a week to respond to the charges after earning the full backing of manager Ronny Deila.

‘I trust my players,’ said the Celtic boss this week before heading off for the club’s Europa League tie in Austria. ‘I know he didn’t do it.

‘He is an honest player and I believe in what he is saying. He has not wasted any energy on that at all. He seems very comfortable.’

Deila, meanwhile, has told Leigh Griffiths that he has to learn to learn to be an athlete 24 hours a day if he is to have a Parkhead future.

Like Tonev, the striker is awaiting the outcome of an investigation into allegations of racism after he was filmed joining in chants before a Hearts-Hibs clash earlier this year.

Bulgarian international Tonev controls the ball during Wednesday evening's training session in Austria

Celtic manager Ronny Deila has backed Tonev by calling the on-loan winger an 'honest player'

Former club Hibs want Griffiths on loan after he travelled to Austria for the 2-2 draw with Red Bull Salzburg – but did not feature.

Asked if Griffiths has a future at the club, Deila said: ‘Leigh knows how he is standing and where the situation is.

‘We have a very good and big squad and we need competition.

‘I’ve always said people have to improve all the time to get the chances and that’s the same for Leigh as the others.

‘We talk all of the time. He’s a nice boy and we have good communication.

‘Leigh really wants to succeed at Celtic. He’s at a very big club, he knows it and this is his chance.

Deila wants striker Leigh Griffiths to prove that he is worthy of a place in his Celtic squad

‘Everyone knows what they have to develop and that’s (the same) for Leigh also.‘Playing matches is important, but being a 24-hour athlete is important as well.

‘There have been no problems with Leigh off the pitch, that’s not why I say this. It’s for everyone.

‘But fitness-wise, he needs to get fitter. Of course, that is about playing, but it also comes from hard work in the gym and also off the pitch.

‘It’s a culture and it takes time to change culture, but we have to work every day to get the knowledge into the players.