The Scots were holding their own in the crunch World Cup qualifier in the Ullevaal Stadium until the 34th minute when the 43-year-old Luxembourg official reduced George Burley's side to 10 men after he booked the Celtic defender for the second time in two minutes.

A night of misery for the Scots followed after Norway defender John Arne Riise fired in the opener from the resultant free-kick.

The crushing defeat meant Burley's side slipped behind Macedonia on goal difference in to third spot.

Scotland now need wins in the final two Group Nine games against Macedonia and Holland at Hampden next month to have any chance of securing second spot and a play-off place.

Scotland captain Darren Fletcher was in no doubt who was to blame for the Oslo defeat, saying: "The lads played well, everyone gave it their all - but in the end the refereeing decisions have changed the game.

"That's so hard to take because you expect top referees to be in charge of games as important as this one. There's a World Cup at stake.

"I don't know how many big games he has to take care of every season in Luxembourg."

However, before leaving Oslo this morning Hamer told Press Association Sport that he was used to criticism, which he claims is usually ill-informed.

"People often criticise me because I come from Luxembourg," Hamer said.

"I might come from Luxembourg but they should know that I referee mostly in the top leagues in France and Belgium.

"But everyone is entitled to their opinion.

"I am used to it but I don't really want to comment on my performance.

"I refereed the game between the same two sides four years ago in Oslo when Scotland won 2-1.

"Funnily enough there was no criticism of me after that game."

Scotland striker Kenny Miller described Caldwell's dismissal as an "horrendous decision," while George Burley and Caldwell's brother, Steven Caldwell, also questioned Hamer's use of his yellow cards.

The Scotland boss claimed that the referee would not have produced the second yellow card if he had realised that he had only just booked the Celtic player.

However, Hamer refuted that notion saying: "There was no hesitation.

"Yes, I did know that I had booked Caldwell a few minutes earlier.

"It wasn't a red card offence, the second incident, but it was a yellow card offence and so he had to go."

Norway striker John Carew also complained afterwards that his effort in the second half had crossed the line before the ball was grabbed by Scotland keeper David Marshall.

However, Hamer said: "I don't know if it was over the line, I haven't seen that incident again."

Meanwhile, Steven Caldwell will see a specialist in his bid to be fit for the visit of Macedonia and Holland.

The Burnley defender was substituted minutes after the break in the Ullevaal Stadium with a groin injury.

Burley admitted he may have to recall veteran Rangers defender David Weir for the game against Macedonia.

Gary Caldwell is suspended and Christophe Berra's hamstring injury, which saw him replaced after coming on as a substitute, could rule him out.

Steven Caldwell, however, is hoping he is fit to play his part in what are do-or-die games for the Scots.

"I really hope to be fit," he said. "I am by no means ruling myself out.

"I have been carrying the groin injury for a while but I couldn't go on.

"I was moving sluggishly and had to do the sensible thing.

"I will see a specialist and do everything to be there against Macedonia.

"I will do the right things and listen to the right people to help but Saturday's game for Burnley might be out of my reach."