Anders Behring Breivik, who killed 77 people in Norway last July, was not psychotic at the time of the twin attacks and can thus be held criminally responsible, a new psychiatric report has found.

"The experts' main conclusion is that the accused, Anders Behring Breivik, is not considered to have been psychotic at the time of the actions on 22 July, 2011," the Oslo district court said in a statement

"That means that he is considered criminally responsible at the time of the crime."

The assessment by psychiatrists Agnar Aspaas and Terje Toerrissen reopens the debate on whether the self-confessed killer can be sent to prison.

The new evaluation counters the findings of an initial probe that found Mr Breivik was suffering from "paranoid schizophrenia", which meant he would most likely be sentenced to psychiatric care instead of prison.

On 22 July, Mr Breivik first set off a car bomb outside government buildings in Oslo, killing eight people.

He then travelled to the small island of Utoeya, northwest of the capital, where he spent more than an hour shooting and killing another 69 people, mostly teenagers.

The victims had been attending a summer camp hosted by the ruling Labour Party's youth organisation.

The conclusions of the second psychiatric evaluation, which was ordered by an Oslo court amid an outcry over the initial exam findings, were published just six days before the Mr Breivik's trial is set to start.

In the end however, it will be up to the Oslo court judges to determine his mental state when they publish their verdict in July, thus deciding whether he will be locked up in a closed psychiatric ward or sent to prison.

In a preliminary court hearing, Mr Breivik denied criminal guilt and suggested his actions were part of a war to save European culture.