Referee Craig Thomson has admitted he made a mistake in not giving a 12th-minute penalty to Celtic in Sunday's Old Firm derby against Rangers.

Shaun Maloney was pulled down by David Weir with his side one goal behind in a game they went on to lose 2-1.

Scottish FA referee chief Hugh Dallas was pleased with Thomson's overall display in the Old Firm derby at Ibrox.

But Dallas said: "He is disappointed at his error of judgement when he decided against awarding a penalty."

"Taking charge of an Old Firm game is both high profile and challenging," said Dallas.

"Referees are well aware that their performance will be judged on calling the major decisions correctly.

"Craig and I have had our post match de-brief.

"Whilst I would compliment Craig for his overall handling of yesterday's encounter, he is disappointed at his error of judgement when he decided against awarding a penalty to the visiting team in the 12th minute.

"Our referees are fitter than they have ever been and our referees are better prepared for matches than they have ever been.

"We are working each and every day with our top officials to make sure that they are in a position to get the big calls right.

"However, mistakes are part and parcel of football. I think that it says a lot for the character and professionalism of Craig that he has been more than willing to hold his hands up on this one."