Confessed Norwegian mass murderer Anders Behring Breivik is due in an Oslo court Monday for a closed door hearing.

Norwegian police will ask the court to extend Breivik's pretrial detention by eight weeks. An Oslo police spokesman said prosecutors will ask that four of those weeks be served in isolation.

Prosecutors say the additional eight weeks are needed to continue preparing formal charges against the 32-year old right-wing extremist, who has confessed to the July 22 massacre that left 77 people dead.

Initially the district court ordered Monday's hearing be open to the public, but an appeals court reversed the decision. The courtroom will be free of survivors, victims' family members, the media and the general public.

Police believe Breivik acted alone on July 22 when he detonated a bomb outside government offices in Oslo and went on a shooting rampage on Utoeya island, 40 kilometers northwest of the capital. But officials are still considering the possibility Breivik may have had some help.