Thousands crowded into Gothenburg cathedral for a special service.

A ceremony also took place at a mosque in the city, and a candle-lit vigil has been held near the burnt-out discotheque where the fire took hold in the early hours of Friday.

The BBC's David Loyn in Gothenburg: "Those in the upstairs room did not have a chance"

Swedish police now say they believe it could have been started by an electrical fault, although they are still examining the evidence.

Officials have have discounted arson as the cause of the blaze, in which up to 190 people were injured.

The fire swept through a Macedonian cultural centre where about 400 young people - many of them Macedonian and Somali immigrants - were attending a Halloween dance.

The hall was only licensed to hold 150 people; one fire exit was blocked.

Police spokesman Bengt Staaf: "We have no proof that it was an arson"

Swedish police have played down suggestions that the fire was started deliberately, saying there is no evidence at this stage to suggest that arson was to blame.

A rescuer at the scene had earlier suggested that the fire could have been started deliberately given the speed with which the flames swept through the brick building.

Many of the dead were Macedonian and Somali immigrants

The Swedish Prime Minister, Göran Persson, has visited the fire site and laid flowers in the burnt-out hall and talked to rescue workers. King Carl XVI Gustav made a statement of condolence.

Police said most victims choked to death on smoke and poisonous gases produced by the blaze.

It is the deadliest fire in modern Swedish history. In 1978, 20 people died in a fire in the town of Boraas.

Eyewitness account

Taxis, cars and buses helped to ferry the injured to hospitals all around Scandinavia

The fire broke out at midnight local time (2300 GMT) in a second floor discotheque held in the building.

Fifteen-year-old Jamal Fawz who was in the disco said the fire seemed to have started from the ceiling as "lamps and loudspeakers fell to the floor."

"It was chaos. Everybody was trying to get out and people trampled on each other on the way to the exit... Others kicked out the windows and jumped out," he said.