"The court has come to the conclusion that Anders Behring Breivik is not, and has not, been subjected to torture or inhumane or degrading treatment," the Oslo court said in its decision.

The verdict said there were "no clear indications that Breivik has been subjected to isolation damage during his prison sentence."

"The court is of the opinion that there is a high risk that Breivik will resort to violence in the future," it added.

In July 22, 2011, Anders Breivik -- a radical conservative -- carried out a bomb attack in Oslo, Norway. He then slaughtered students on Utoya Island located near Oslo. In total, 77 people died and more than 200 others were wounded.

The victims include Gizem Dogan, a 17-year-old woman of Turkish descent.