Anders Behring Breivik, who has admitted to twin attacks in Norway that claimed 77 lives a month ago, was brought Friday to an Oslo court that was to rule on whether to extend his solitary confinement, DPA reported.
The hearing - to be held behind closed doors - was due to begin at 1 pm (1100 GMT).
On July 25, three days after his attacks, Breivik was remanded in custody to eight weeks, of which four weeks were in solitary confinement.
Police want to extend the solitary confinement a further four weeks and requested a closed-door hearing since they could not rule out that Breivik might have had accomplices.
His attorney Geri Lippestad said Breivik said it was hard to be isolated.
"He says he has lost his spark," Lippestad told the Dagbladet daily.
Breivik has admitted to detonating a car bomb that killed eight people in central Oslo and a shooting that claimed 69 lives at a youth camp organized by the Labour Party.