A new psychiatric examination has found that confessed mass killer Anders Behring Breivik is not criminally insane, contradicting an earlier assessment.

The new conclusion comes just six days before the 33-year-old Norwegian goes on trial on terror charges for the bomb and shooting rampage on July 22 that killed 77 people in Norway.

It conflicts with an earlier examination that diagnosed Breivik as psychotic and prompted prosecutors to say he should be committed to a mental institution instead of prison if convicted.

Breivik has confessed to the attacks, but denies criminal guilt. He claims the attacks were necessary in what he calls a civil war against Islam in Europe.