Police were hunting on Sunday to see if a possible second gunman took part in the shooting massacre and bomb attack on Friday that traumatized a normally peaceful Nordic country.

In his first comment via a lawyer since he was arrested, 32-year-old Norwegian Anders Behring Breivik expressed willingness to explain himself in court at a hearing likely to be held on Monday about extending protective custody.

"He has said that he believed the actions were atrocious, but that in his head they were necessary," lawyer Geir Lippestad told independent TV2 news.

Police said Breivik gave himself up after admitting to a massacre in which at least 85 people died, mostly young people attending a summer camp of the youth wing of Norway's ruling Labour Party on an idyllic island.

Breivik was also arrested for the bombing of Oslo's government district that killed seven people hours earlier. Norway's toughest sentence is 21 years in jail.

Survivors, relatives of those killed and supporters planned a procession to mourn the dead at Sundvollen on Sunday, near the island where the massacre took place.

King Harald would attend a service in Oslo cathedral, a few hundred meters (yards) from where a bomb devastated government buildings including the offices of Labour Prime Minister Jens Stoltenberg.

Reuters