Celtic coach Johan Mjallby reckons Scottish refs are too soft.
Willie Collum, at the centre of controversy during the Hoops' 1-1 draw at Hamilton, is fourth official at Easter Road today as Celts face Hibs.
Craig Thomson - who filed the report which led to boss Neil Lennon's six-game ban - is the ref.
Mjallby rapped: "I think referees have to be mentally tougher. We know they are going to make mistakes. It's going to happen in the future, we don't have a perfect world.
"I think most of them are competent enough, but maybe they should be mentally tougher.
"They also have to understand even if it was Kilmarnock v St Mirren on Wednesday night, and they made the same mistakes, you can't tell me Mixu Paatelainen wouldn't have been a bit annoyed with the referee."
Asked how referees could be made mentally tougher, Mjallby replied: "Good question!
"I don't think there's a referees' school, is there?
"I'm quite sure they have a lot of meetings and maybe they can sit down and discuss things.
"I know maybe the criticism has been over the top, but refs need to understand that when you work with a team there are so many emotions and we are going to be frustrated about it."