Dozens killed in fire at Swiss ski resort bar during New Year party

"Several dozens" of people were killed and more than 100 were injured when fire ripped through a crowded bar in the Swiss ski resort of Crans-Montana early Thursday as revellers celebrated the new year.

The blaze started around 01:30 at Le Constellation bar, where more than 100 people had gathered, Valais cantonal police said. The venue has a capacity of 400 people.

Police first stated that "several people lost their lives and others were injured" in what they described as a serious incident. The toll was later updated, but the actual number of casualties remains unclear.

Police spokesman Gaëtan Lathion earlier said authorities were seeing many casualties. "More than a hundred people were in the building, and we are seeing many injured and many dead," he told reporters.

Earlier reports described an explosion, but police later characterised the event as a fire of undetermined origin.

Swiss media reported the fire may have been caused by pyrotechnics during a concert, though authorities stressed the cause remains under investigation.

Medical sources told local broadcaster RTS that hospitals across French-speaking Switzerland were overwhelmed treating burn victims.

Police, firefighters and multiple helicopters were deployed to the scene. Emergency services brought the fire under control while rescue operations continued.

Authorities sealed off the area completely and imposed a no-fly zone over Crans-Montana.

"We're just at the beginning of our investigation, but this is an internationally renowned ski resort with lots of tourists," Lathion said.

Authorities scheduled a news conference for 10:00 local time Thursday.

Crans-Montana sits in the Swiss Alps, some 40 kilometres north of the Matterhorn, or about two hours from Bern.

The upscale resort town of some 15,000 permanent residents attracts international visitors for its ski slopes, fine dining and lively après-ski scene.

Crans-Montana is scheduled to host FIS World Cup speed skiing events later this month.