Norway held a minute's silence at noon (1000 GMT) Monday to commemorate the victims of the twin attacks that claimed almost 100 lives last week, dpa reported.
Trading halted on the Oslo bourse, and taxis, trains and public transport stopped, as did activity at workplaces and schools across the country of 4.9 million people.
In Oslo, King Harald, Prime Minister Jens Stoltenberg and others signed a book of condolence after taking part in the tribute at University Square.
Neighbouring Denmark, Sweden and Finland followed suit. Flags were at half-mast in Norway and Sweden, and trading was also halted on the Stockholm bourse, the largest in the Nordic region.
Anders Behring Breivik, 32, has been charged in connection with the attacks. A court custody hearing was due an hour after the minute of silence was held.