Mass killer Anders Breivik will be sent to a psychiatric hospital and not prison after doctors decided he was insane when he murdered 77 people in a bomb and shooting rampage in Norway.

An evaluation ordered by an Oslo court found that Mr Breivik was “psychotic” during the July 22 attacks – the country’s worst peacetime massacre – which means he is not mentally fit to be sentenced to prison, prosecutors said.

The conclusions, which will be reviewed by a panel of forensic psychiatrists, contrasted with comments made by the head of that board after the attacks. Psychiatrist Tarjei Rygnestad at the time said it was unlikely that Mr Breivik would be declared legally insane because the attacks were so carefully planned and executed.

“The conclusions of the forensic experts is that Anders Behring Breivik was insane,” prosecutor Svein Holden said, adding Mr Breivik was in a state of psychosis during the attacks.

In their report, the experts describe a man “who finds himself in his own delusional universe, where all his thoughts and acts are governed by these delusions,” Mr Holden said. “They conclude that Anders Behring Breivik during a long period of time has developed the mental disorder of paranoid schizophrenia, which has changed him and made him into the person he is today.”

In Norway, an insanity defence requires that a defendant be in a state of psychosis while committing the crime with which he or she is charged. That means the defendant has lost contact with reality to the point that he’s no longer in control of his own actions.