The right-wing extremist who confessed to killing 77 people in a bomb and shooting rampage in Norway is not criminally insane, a psychiatric assessment found Tuesday, contradicting an earlier assessment.

The new conclusion comes just six days before Anders Behring Breivik is scheduled to go on trial on terror charges for the massacre on July 22.

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.

The new assessment was made by psychiatrists Terje Toerrissen and Agnar Aspaas on a request from the court after widespread criticism against the first diagnosis.

"The main conclusion of the experts is that Anders Behring Breivik is found to be not psychotic during the time of his actions on July 22, 2011," the Oslo court said in a statement.

Breivik has confessed to setting off the bomb in downtown Oslo, killing eight, and opening fire at a youth camp outside the Norwegian capital, killing 69. But he denies criminal guilt, saying the attacks were necessary in what he calls a civil war against Islam in Europe.

The court will take both psychiatric assessments into account during the trial which starts Monday and is scheduled to last 10 weeks. If Breivik is found guilty but ruled psychotic, he will subjected to compulsory psychiatric care instead of imprisonment.