Oslo: Norwegian Prime Minister Jens Stoltenberg on Friday presented a new commission appointed to determine what lessons should be drawn from the July 22 twin attacks to ensure nothing similar happens again.

"Thousands of people across the country need help and care. For them, it is vital to get answers to the questions: What happened? And why did it happen?" Stoltenberg said as he presented the commission, three weeks to the day after rightwing extremist Anders Behring Breivik killed 77 people.

"It is also important for us as a nation. We must draw information from these terrorist attacks. The goal is for this never to happen again. The goal is more security," he told reporters.

Survivors, relatives of victims and media have asked a growing number of questions about the attacks, especially the time it took police to arrest the killer and halt his rampage, and the intelligence service's failure to spot Behring Breivik during his years of preparations for the massacre.

"We need an overview of all the things that worked well, ... but also of all that did not work well, openly and without embellishment," Stoltenberg said.

The 10-member commission, which has not been tasked to probe the attacks but simply to go through them and evaluate the response, will be headed by lawyer Alexandra Bech Gjoerv.

Two former police officers, a former intelligence service chief, a doctor, an international terrorism expert and a communications professor figure among the commission members.

The commission will begin work immediately and is scheduled to complete its evaluation by August 10, 2012.

On July 22, Behring Breivik, 32, first set off a car bomb outside government offices in Oslo, killing eight people, before going on a shooting spree on the nearby island of Utoeya where the ruling Labour Party's youth wing was hosting a summer camp, killing another 69, many of them teenagers.