A police committee on Friday cleared Norwegian officers of major failures for their response to the massacre of 77 people this summer, but families of the victims called the inquiry too weak.

Police have been criticized for a series of mishaps that slowed them down as they tried to reach the island where right-wing killer Anders Behring Breivik slaughtered dozens of youths. Olav Soenderland, the head of the committee that evaluated police action during the terror attacks, defended their response, saying they acted as quickly as possible.

"We have studied the situation where there was a need for the fastest possible action," Soenderland told reporters. "We haven't been able to point to any points of improvement there."

It took 90 minutes for police to reach the island. Officers struggled after a boat broke down because it was overloaded and all police helicopter pilots were on vacation at the same time. Breivik told investigators he was surprised and had expected a SWAT team to swoop down within 15 minutes of his attack.

A spokesman for the relatives and families of the victims said the internal investigation lacked self-criticism.

"They should have asked themselves whether they, hypothetically, could have acted faster," Trond Henry Blattmann said. "If they had done so they might have come up with a different answer."

Soenderland said beside the boat breakdown there were few reasons to criticize the operation.

"That the boat was overloaded is a fact," he said, but he declined to comment on how the police could have acted more efficiently or faster. "Our task is not to evaluate a hypothesis," he said.

Survivors have said they struggled to get through to police emergency lines shortly after Breivik began his shooting spree on the island because operators rejected calls because they were focused on the bombing in downtown Oslo at around the same time.

Soenderland acknowledged there was room to improve the capacity of police emergency numbers, which is already under way, but said that it had not affected police response at the time.

"They did everything they could," he said of the officers who took part in the operation.

The committee's findings will be included in an evaluation report to be presented in March by an independent government-appointed July 22 commission.

Breivik has confessed to the killings but denies criminal guilt because he believes the massacre was necessary to save Norway and Europe.