Canadian police are searching for five French tourists who fell through ice on snowmobiles while on an excursion in northern Quebec, as provincial authorities pledged to tighten safety measures on the use of the recreational vehicles.

After another fruitless night of searching, the effort to find the five resumed at dawn in an area east of Saint-Jean Lake near the town of Saint-Henri-de Taillon.

Two snowmobiles similar to those used by the original group of eight tourists and their Canadian guide were found on Wednesday at the bottom of Saint-Jean Lake near where the accident occurred.

Investigators are still hopeful that the French tourists managed to find refuge on an island or a chalet but have been unable to communicate, provincial police spokesman Hugues Beaulieu said.

"There a still certain points to check," he said. "But the more time passes, the less likely this becomes." 

A third team of divers, with a small submarine equipped with sonar, joined the search at sunrise. Dozens of police officers, backed by two helicopters, also were deployed in the area, which is about 225km north of Quebec City.

The snowmobiles crashed through ice Tuesday evening at a dangerous spot where Saint-Jean Lake funnels into a river. The area is off limits to snowmobiles because the ice is thinner there.

Police said they were alerted by two of the tourists who had rescued a third from the water.

The 42-year-old guide, Benoit L'Esperance, was pulled out by emergency response teams and taken to hospital, but later died.

The surviving three tourists were briefly hospitalised and treated for exposure and shock.

Investigators do not know why the group left the approved paths to venture "off-piste" at nightfall, but some experts believe they may have been trying to take a short-cut to their destination.

Canadian police have not released the identity of the missing snowmobilers, but French media identified one as Gilles Claude, the father of three international biathletes.

"There was a tragic accident in Canada involving my father," said one of the sons, Fabien Claude, in an interview on the L'Equipe channel after winning a bronze medal at yesterday's Biathlon World Cup in Slovenia.

"This podium is for him, I am sure he is proud of us and I am proud of what I have done today," he told L'Equipe, speaking with his brother Florent by his side.

Shocked by the accident, the Quebec provincial government said it wants to make training mandatory for guides and tourists who use snowmobiles.

"Lessons will be learned and actions will be taken to prevent such tragedies in the future," said Quebec Tourism Minister Caroline Proulx.

Ms Proulx expressed the government's "desire" to "make the training of guides for off-road vehicles and tourists who hire them from a company mandatory," she said, commenting on measures that have been expected for weeks.

In addition, effective from yesterday, nature and adventure tourism businesses in the province will require quality and safety certification in order to be eligible for financial assistance from the tourism ministry.

Quebec, with some 33,000km of marked trails in postcard settings, is popular with snowmobile enthusiasts, especially foreigners.

According to the Federation of Snowmobile Clubs of Quebec, snowmobile tourism generates more than CAN$3 billion a year for the province, and creates jobs for more than 14,000 people.

Each year, however, an average of 20 people die in Quebec due to snowmobile accidents.

In February 2019, two French tourists, a mother and her son, were killed while snowmobiling in a Quebec park.