Celtic are considering expressing formal concerns about referee standards to the Scottish Football Association ahead of Sunday's Old Firm derby. A club source has told BBC Scotland of their frustration about major decisions after analysing footage - including the last two games against Rangers.

But SFA president George Peat has rejected the claims as "inaccurate".

"We are considering contacting the SFA to highlight our concerns at some of the major decisions we feel have gone against us this season," said the Celtic source.

"The refereeing performances are a concern and a frustration to us."

The Hoops also have concerns about offside decisions given against Robbie Keane, their recent loan signing from Tottenham Hotspur.

"It seems that officials are struggling to keep up with his pace," said the source.

"Several key off-side decisions have gone against him purely because of his speed."

Celtic and SFA officials have met to discuss the Glasgow club's concerns, but the leak from the club has angered Peat.

"We find it disappointing and somewhat bizarre that, in the build-up to an Old Firm derby, an unnamed Celtic 'source' would seek to exert additional pressure on match officials by issuing ill-timed and fundamentally inaccurate comments," said the SFA president.

"The validity of these comments is questionable in any case, since the 'source' is not courageous enough to put his name to them.

"In actual fact, discussions between the Scottish FA and Celtic have taken place, but the contents of these discussions will remain private, as was agreed with the club.

"I am sure the Celtic chief executive, Peter Lawwell, will be concerned by the fact that someone has elected to speak on behalf of his club, seemingly without consent, and therefore undermined his authority."