Norwegian authorities are planning to convert part of a high-security prison outside Oslo into a psychiatric unit in case Anders Behring Breivik is found insane.

The plan means Breivik will remain at the Ila prison whatever the outcome of his trial, Norwegian tabloid Verdens Gang reported Thursday.

Deputy health minister Robin Koss said, "We are building a high-security psychiatric hospital in Ila." He added that formal approval was pending.

The proposed unit would be located in the same area of the prison where Breivik is housed currently.

Breivik has admitted killing 69 people at a political youth camp on Utoya island and another eight in a bomb attack on a government building in Oslo on July 22 last year.

He refuses to plead guilty, claiming the killings were "cruel but necessary."

A verdict is expected in July or August.