Anders Breivik's hour-long gun massacre on Utoya island could have been stopped sooner, investigators have concluded.
A commission set up to review the authorities' response to his twin attacks in Norway last year has severely criticised both the police and the government.
On July 22, 2011, Breivik set off a car bomb outside government buildings in Oslo, killing eight people, before going to the nearby island of Utoya where he spent more than an hour gunning down 69 people.
Despite the island being just 600 metres away from the mainland, it was 35 minutes between the first police patrolís arrival at the shore and the moment when an elite police squad disembarked on Utoya.
Commission chief Alexandra Bech Gjoerv described the delay as "unacceptable".
The police's elite Delta force, which arrived from Oslo, also suffered delays in reaching the island. Their simple rubber dinghy was overloaded and broke down, forcing them to borrow two pleasure boats.
According to the commission, if all procedures had been followed, police could have been on the island 12 minutes earlier.
The bomb attack in Oslo could also have been prevented, the commission said.
The 10-member panel pointed out that due to bureaucratic red tape the street outside the government office complex had never been closed to traffic despite recommendations dating back to 2004.
This enabled Breivik to park a small rental truck carrying 950kg of explosives at the foot of Prime Minister Jens Stoltenberg's seven-storey office building.
Stoltenberg was working at his official residence at the time and was not injured in the attack.
More than three hours then passed between the Oslo bombing and Breivik's arrest on Utoya, where he spent one hour and 15 minutes gunning down his victims.
"The authorities' ability to protect the people on Utoya island failed. A more rapid police operation was a realistic possibility," the panelís report said.
It added: "The perpetrator could have been stopped earlier on July 22."
Stoltenberg said he regretted the "significant shortcomings" highlighted in the report but ruled out his own resignation or that of any members of his cabinet.
Police reiterated their apology for not arresting Breivik sooner, but also said there would be no resignations.
Breivik's 10-week trial concluded in late June and a verdict is scheduled to be announced on August 24.