A lay judge in the case of Anders Behring Breivik has been caught on camera playing solitaire on his computer during proceedings.

Lay Ernst Henning Eielsen was snapped playing the card game as Professor Mattias Gardell of Uppsala University in Sweden gave evidence.

It is believed the incident will have no negative consequences for the trial after a court spokeswoman said Eielsen's gaming activity did not mean he was not paying attention to the hearings.

Anders Behring Breivik killed 77 people on July 22, killing eight with a car bomb outside the government headquarters in Oslo, then gunning down 69 people, mostly teenagers, at the ruling Labour Party's summer camp on Utoeya Island.

The court's main task in the ten-week trial is to decide whether Breivik is sane and whether he should be sent to jail or a psychiatric institution.

The five judges, including three lay judges, will take a final decision on his sanity at the end of the trial, expected in late June.