Anders Behring Breivik was declared insane Tuesday and may be sentenced to enforced treatment for killing 77 people in Oslo in July.

From the start, he has admitted his twofold assault on Oslo government administrative centres and a Labour Party youth camp outside the Norwegian capital.

The account was established through a total of 13 consultations with Breivik over a 36-hour period. The assessment, which still has to be approved by the Board of Forensic Medicine, may lead to the 32-year-old extremist being placed in obligatory psychiatric treatment rather than prison, possibly for life.

It has been confirmed that Breivik has a medical condition that is the cause of his paranoid schizophrenia and is highly ''delusional'' according to a court ordered evaluation.

Chief Prosecutor Svein Holden said as much at a press conference in Oslo, after presenting the 243-page report by forensic psychiatrists Torgeir Husby and Synne Soerheim.

Breivik has confessed to the shootings at the Utoeya Island youth camp that killed 69 children (a few as young as 14) and to blowing up a car bomb that took eight lives.

Breivik said that he wanted to cause what could be the ''greatest possible loss'' to the ruling Labour Party and was extremely livid about a manifesto posted on the Internet against ''cultural Marxism'' and ''Islamization.''

Earlier this month an Oslo court lengthened his custody by 12 weeks to Feb. 6 while limitations on communications, virtual or otherwise, were drawn out by eight weeks. Court-ordered on media was extended by four weeks.

Breivik has declined to concede the authority of the court and has insisted on his release. The judge denied an appeal by Breivik to speak to survivors and family of the victims.