The 32-year-old Norwegian who recently confessed to killing 77 people will spend another four weeks in isolation. The killings were the worst mass violence in Norway since World War Two.

A judge Friday rejected Anders Behring Breivik's complaint that his solitary confinement was boring, monotonous and “a sadistic method of torture.”

Judge Hugo Abelseth also told reporters following the hearing he agreed with police concerns that Breivik would have an opportunity to tamper with evidence if he is not isolated.

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.

The hearing was closed to the public, but those inside told reporters Breivik was dressed in a dark suit and shackled. Breivik had earlier requested he be allowed to wear a tuxedo to the hearing but that request was denied.

Friday's hearing came as relatives of many of those killed began visiting Utoeya island under heavy police protection. More than 1,000 people are expected to visit the crime scene over the next two days, ahead of a national memorial service Sunday in Oslo.

Breivik's lawyer has said his client admits the killings, but denies criminal responsibility because he believes the massacre was needed to save Norway and Europe from an influx of Muslims, and to punish politicians for embracing multiculturalism.

Last Saturday, police brought Breivik back to Utoeya island as he retraced the eight-hour route he took the day of the shooting. Authorities say the entire reenactment was filmed for possible use in court proceedings.

Video shows Breivik pointing out locations along the route and simulating shots into the water, where scores of teenagers tried to escape the deadly onslaught.