OSLO, Norway - Norway's Justice Minister Knut Storberget stepped down Friday, after postponing his resignation in the wake of a massacre by a right-wing fanatic, the prime minister said.

Jens Stoltenberg said Knut Storberget asked to resign some time ago for personal reasons, but agreed to stay on in the aftermath of Anders Behring Breivik killing 77 people on July 22.

Breivik has confessed to detonating a car bomb in the capital, Oslo, killing eight people, and then massacring 69 in a shooting rampage on Utoya island outside the city. He denies criminal responsibility and is awaiting trial in solitary confinement.

Storberget's departure came a day after he presented preliminary findings from an investigation into the police response to the July 22 attacks, which showed Breivik was arrested more that five minutes later than previously thought.

The report also highlighted that officials had alerted police near Utoya that Breivik could be travelling into their region, more than an hour before the island shootings.

Arne Seland, a lawyer for the victims, welcomed Storberget's resignation.

"It would be strange if July 22 didn't have anything to do with it," the Dagbladet daily quoted Seland as saying.

However, the prime minister and other government officials insisted Storberget's decision was personal.

"He told me some time ago that he wanted to leave," Stoltenberg told local news agency NTB. "I felt it important that he should present the report and asked him to stay on for that. I asked him to continue."

Norwegian media said that Storberget, 47, with three small children, has said he wants to spend more time with his family.

Storberget's position will be taken by Defence Minister Grete Faremo, who is being replaced by a state secretary.

It was the second shuffle this year in the Labour-led government after the influential oil and energy minister resigned in March following criticism of two widely unpopular energy projects.