A Norwegian anti-immigration radical has admitted to killing 77 people at youth camp in July, but he denied any guilt, saying he was a military commander in a far-right resistance movement.

Anders Behring Breivik, who spoke in open court for the first time on Monday, sat with his eyes mostly downcast and occasionally bit his lip in a packed hearing to extend his pre-trial detention period.

At one point Breivik attempted to address survivors of Norway's biggest modern-day massacre, but the judge cut him off.

Al Jazeera's Sonia Gallego reports.