OSLO — Far-right gunman Anders Behring Breivik stuck to his decision not to appeal a terror conviction and prison sentence Friday, formally closing the legal proceedings for Norway’s worst peacetime massacre.

Breivik, whose bomb and shooting attacks shocked Norway on July 22 last year, was sentenced two weeks ago to a 21-year prison term that can be extended for as long as he is considered a danger to society.

Breivik, 33, told the court at the time that he would not challenge the ruling and had not changed his mind on Friday, the last day of the appeals period, defense lawyer Geir Lippestad said.

‘‘There is no doubt that the July 22 case is over today,’’ Lippestad told reporters after meeting his client in prison.

Breivik set off a bomb that killed eight people and injured more than 200 in Oslo’s government district, before opening fire at the left-leaning Labor Party’s annual youth camp, killing 69, most of them teenagers, on Utoya island.

Throughout his trial, he showed no remorse and accused his victims of betraying Norway by embracing a multicultural society.