Norwegian police are not "completely ruling out" that gunman Anders Behring Breivik had help from others in his gun and bomb attacks that killed more than 90 people.
"We cannot completely, and I stress completely, rule out that others were involved in what happened," police attorney Christian Hatlo told a news conference when asked if there were other "cells".
Earlier on Monday, Breivik told a court in Oslo that "there are two more cells in our organisation", according to the judge who ordered him to solitary confinement.
Breivik pleaded not guilty to one of the deadliest modern mass killings in peacetime, saying he wanted to save Norway and Europe from a Muslim takeover and send a strong signal, but was not trying to kill as many as possible, Judge Kim Heger said after a closed court hearing. Breivik could tamper with evidence if released, and will be held for at least another two months without access to visitors, mail or media, the judge said.
Breivik made clear in an Internet manifesto that he planned to turn his court appearance into theatre, preparing a speech for his appearance in court even before launching the attacks, and then requesting an open hearing in which he would wear a uniform. Both of those requests were denied.
The suspect staged the bombing and youth camp rampage as "marketing" for his manifesto calling for a revolution that would rid Europe of Muslims, he said. A judge ordered the hearing closed, denying the suspect the chance to the public stage he wanted.
Reporters and locals thronged the courthouse on Monday ahead of the hearing for their first glimpse of Breivik since the assault.
When one car drove through the crowd, people hit its windows and one person shouted an expletive, believing Breivik was inside. The hearing ended after about 35 minutes.