The trial in Oslo of six people charged in connection with the theft of Edvard Munch's painting The Scream has been adjourned until Thursday.
The Scream and Madonna have not been seen since 2004
Five of the accused are charged with aggravated robbery, while the sixth is accused of dealing in stolen goods. All six defendants pleaded innocent.
The Scream, along with another work, Madonna, was taken in a daylight raid on Oslo's Munch Museum in August 2004.
According to a police spokesman, the trial is expected to last five weeks.
Shortly after the hearing began, the defendants' lawyers asked for an adjournment to examine phone-tap evidence, which they claimed was provided too late by prosecutors.
The judges granted the request, and ordered the trial to resume on Thursday.
The five suspects charged with aggravated robbery could face up to 17 years in prison if found guilty.
The five include Stian Skjold, 30, one of the suspected robbers; Petter Tharaldsen, 34, the alleged getaway driver; Bjorn Hoen, 37, the suspected "mastermind" and two presumed accomplices Petter Rosenvinge, 38, and Morten Hugo Johansen, 39.
A sixth man, Thomas Nataas, 35, accused of handling stolen goods, could face up to six years in prison.
He owned a bus where the two paintings were allegedly hidden for a month after the robbery.
Missing art works
The paintings were moved to an unknown location and neither of the stolen works has been seen since, despite an international search and the offer of a reward.
With the 1893 works still missing, the prosecution case rests largely on phone-tap evidence. A police lawyer said he did not expect the trial to lead to the paintings' recovery.
The paintings are valued at more than £10m.