Norway is paying tribute on Sunday to 77 people killed in last month's bombing and shooting massacre by a right-wing extremist.

A memorial service at the Spektrum Arena in central Oslo, to be broadcast live on national television, will be attended by the families of victims and survivors of the July 22 car bombing and shooting spree.

Norway's King Harald and Prime Minister Jens Stoltenberg will address the ceremony, to be attended by government members, lawmakers and leading politicians from neighboring Nordic countries.

The ceremony includes performances by some of Norway's top names in music, including 1980s pop group A-ha, soprano Sissel Kyrkjeboe, rap group Karpe Diem and the Norwegian Radio Orchestra.

Anders Behring Breivik has admitted killing 77 people last month when he first detonated a truck bomb outside government offices in Oslo, and then went on a meticulously planned shooting spree at a youth camp on the island of Utoya, some 25 miles (40 kilometers) away.

Breivik, 32, denies criminal guilt because he believes the massacre was necessary to save Norway, claiming it was aimed at purging Europe of Muslims and punishing politicians who have embraced multiculturalism.

Breivik was arrested on Utoya 90 minutes after he began his deadly attack. Earlier this week, an Oslo court extended his isolation detention by another four weeks.

On Saturday, some 1,000 survivors and relatives traveled to Utoya, accompanied by police and medical staff, to face the painful memories of the scenes of the shootings. Their visit followed a similar one Friday by 500 relatives of the deceased.

One of the survivors, Stine Renate Haaheim, said her feelings ranged from emptiness and extreme grief to joy when she returned on Saturday to the island, used as a recreational center by Norway's ruling Labor Party.

"There was an extreme mix of feelings because it was very difficult and we are still in grief, but at the same time I was looking forward to seeing Utoya," she told the AP after the visit. I was hoping that in some kind of way it will still be the same island as it used to be"

The hardest part was seeing where her friends died, the 27-year-old lawmaker said.

"We started going around to all the places where our friends were killed and just taking a minute of silence and trying to remember all the good times we had with them and that was extremely hard, I think it's not possible to explain the feelings," Haaheim said, fighting back tears.

Sunday's memorial service marks an end to a month of mourning in the Scandinavian country that was shocked by the attacks in a prosperous and generally tolerant and tranquil society.