A Norwegian court has found confessed mass killer Anders Behring Breivik sane in the commission of twin attacks last year that killed 77 people.

The verdict Friday means that Breivik will go to prison for 21 years, a sentence that could be extended beyond that for as long as he is considered dangerous. The prosecution had wanted an insanity verdict so that Breivik would be sent to a mental hospital.

Breivik, who had said he wanted to be ruled sane, told the court Friday he is sorry he did not kill more people. He has said he was acting to protest multiculturalism in Norway and what he sees as a Muslim invasion of Europe.

Breivik confessed to the killings that took place July 22, 2011, during a bombing on a government building in Oslo and a shooting rampage at a nearby political youth camp. He underwent two psychiatric evaluations, with one ruling him mentally incompetent and the other ruling him sane.

Breivik's defense lawyer says his client would not appeal the prison sentence.

Eight were killed in the bombing and 69 people – mostly teenagers – were shot to death at the youth camp on Utoeya Island.

Breivik has been in prison for more than one year. The judge said his time already served would be deducted from his sentence.