Thirty-two people were presumed to have died in a fire that swept through a wooden retirement residence in the eastern Canadian province of Quebec on Thursday, police said on Saturday.

Ten bodies have been recovered and 22 people are still missing. The disaster looks set to be the second worst to hit a Canadian seniors' home after a 1969 blaze in Quebec that killed 54 people.

Police, pressed about reports a cigarette had started the fire, said they still had no idea what caused Thursday's blaze in the Residence du Havre in L'Isle-Verte, a town of 1,500 people on the St Lawrence River northeast of Quebec City.

Special teams are using steam and hot air to melt layers of ice up to two feet (60 cm) thick that encases many of the bodies. The ice formed after firemen sprayed vast amounts of water on the blaze in freezing temperatures.

Police said earlier in the day that "we can assume the worst" about those still missing more than two days after the fire. Most of the residents were 85 or over and some needed wheelchairs or walkers to move around.

In the aftermath of the disaster, attention has focused on the fact that only part of the residence was equipped with sprinklers, and that provincial law did not require a sprinkler system there.

Quebec police have declined to comment on media reports that the fire may have been caused by a cigarette in a resident's room. One report said a night guard at the home saw thick smoke coming from a second-floor room.

"Investigators are looking at all the hypotheses. There is not one particular hypothesis that is the best one. We have heard rumors ... but they are only rumors," police spokesman Michel Brunet told reporters later in the day, saying it could take months to determine the cause of the disaster.

The residence's website says the facility is smoke-free.

The temperature, which had hovered around minus 22 Celsius (minus 8 Fahrenheit) on Thursday, rose to minus 7 C on Saturday. It was due to drop to minus 17 C on Sunday, according to the federal environment ministry's website.

In a bid to speed up the process of recovery, the special teams on Saturday started using machinery designed to de-ice ships. The equipment produces extra-hot air.

Brunet said the teams would work under canvas tents to concentrate the heat on the ice rather than letting it dissipate into the atmosphere.

"We will work slowly. We have evidence to recover and that will take time," he said, repeating a call for eyewitnesses to produce any video footage or pictures they may have taken during the early stages of the fire.

Three of the victims have been identified, among them a woman of 95 and another of 82.

A memorial service will be held in the town on Sunday at 2 pm (1900 GMT). Local priest Gilles Frigon said the church was there for community members in good times and bad. - Reuters