Mass killer Anders Behring-Breivik has been denied permission to attend his mother's funeral in Norway.

The 34-year-old right-wing extremist is serving a 21-year jail term for killing 77 people in attacks back in 2011.

He is being held under strict prison conditions.

Officials at the high-security jail near Oslo decided to extend his strict security today, and denied his request to attend the funeral.

His 66-year-old mother died last week after a long illness.