A Norwegian court has heard the autopsy reports of the first victims of a youth camp massacre that left 69 people dead on Utoya island.

Anders Breivik, who has admitted to the massacre and a bombing in Oslo, listened impassively as a police inspector and coroner described the gunshot wounds the far-right fanatic inflicted on his victims on July 22.

In an attempt at personifying the dead in Norway's largest peacetime massacre, attorneys for the victims showed pictures from their lives, and read descriptions of them from their families to audible sobs from the bereaved in Oslo's district court.

In his introductory remarks, coroner Torleiv Ole Rognum said the median age of the Utoya victims was 18.

Breivik claims the victims were traitors.