Anders Behring Breivik told police he had "several targets" in mind when they quizzed him after the attacks that killed 77 people, police prosecutor Paal-Fredrik Hjort Kraby said Saturday.
But Hjort Kraby refused to confirm a press report that they included Norway's royal palace and the headquarters of the governing Labour Party.
"During his interrogations he said in general terms that he was interested in other targets," the prosecutor told a press briefing.
"They were targets which would seem natural for a terrorist," he said, declining to give details.
Behring Breivik, 32, a right-wing extremist, confessed to a shooting attack on a Labour Party summer camp on the island of Utoeya which left 69 people dead on July 22, and a car-bomb blast in Oslo earlier the same day which killed eight.
The tabloid Verdens Gang (VG) earlier Saturday quoted Hjort Kraby as saying, "During his interrogation, he said that he had planned to attack other targets, but on July 22 it was only the seat of government in Oslo and Utoeya."
According to VG, the royal palace was a target because of its symbolic value, and Labour headquarters because of the party's role in creating the multi-cultural society so loathed by Behring Breivik.