OSLO (AFP) - Norway's parliament slammed authorities over Anders Behring Breivik's deadly 2011 rampage in a vote on Tuesday that was its harshest criticism yet of the ruling coalition's handling of the attacks.

The lawmakers, who included members of the centre-left coalition, however stopped short of calling for a motion of no confidence over the official response to the right-winger's massacre of 77 people.

"The Storting finds it censurable that the authorities before and during the terrorist attacks of July 22, 2011 didn't implement more security measures and interventions that could have impeded the terrorist attacks and protected people at the government's headquarters and at Utoeya," the motion stated.

The vote comes six months ahead of a general election due in September and could weaken the sitting government.

Breivik first detonated a bomb outside the building housing Prime Minister Jens Stoltenberg's office and then opened fire on the Labour party's summer youth camp on the island of Utoeya.

He accused his targets facilitating multiculturalism and is serving the maximum jail sentence.

An independent commission concluded that the Oslo bombing could have been averted if the street outside the government building, Grubbegata, had been closed to traffic as had been decided several years earlier.

The opposition had called for the government to be specifically named in a more strongly worded motion, but the toned-down text adopted by parliament on Tuesday simply referenced "the authorities".

The minister tasked with overseeing the security of government buildings, Ms Rigmor Aasrud, meanwhile apologised on Tuesday for the failure to close Grubbegata before the attacks took place.

"In hindsight, there is no doubt that the closure of Grubbegata took too long," she said.

Mr Stoltenberg apologised in August for errors made in the response to the attacks.