Anders Behring Breivik was questioned for 10 hours on Friday to verify details from previous sessions and answer new points.
Police would not confirm reports that he had also wanted to attack the palace and Labour Party headquarters.
Funerals have begun for the 77 people killed in the attacks.
Mr Breivik, an anti-Muslim extremist who blamed Labour for increased immigration, is believed to have single-handedly shot dead 69 people at a party summer camp on the island of Utoeya, hours after killing eight with a car bomb near government buildings in central Oslo.
The attacks on Friday 22 July traumatised Norway, one of the most politically stable and tolerant states in Europe.
Police lawyer Paal-Fredrik Hjort Kraby said the suspect had talked about other targets.
“In general, I would say that he had in his plans other targets but on this day it was only these two which were successful,” he told reporters on Saturday.
He described Mr Breivik as “more than willing to co-operate… more than willing to explain himself”.
Without citing its sources, Norwegian tabloid Verdens Gang reported that the suspect had considered attacking the royal palace because of its symbolic value, and Labour HQ because of his loathing for the party.
On Friday, Mr Breivik’s lawyer, Geir Lippestad, told Aftenposten newspaper that his client had harboured “several projects of different scale for that Friday”.
“Things happened that day, which I don’t want to go into, which meant events unfolded differently from what he had planned,” he added.
He said his client continued to show no remorse, saying the killings were “a necessary act . . . a war against the rule by Muslims”.
Police are believed to have been checking targets identified by Mr Breivik in his manifesto, which outlines both his extremist ideas and details his preparations for attacks.
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