Investigators said on Friday that they believe sparkling candles atop Champagne bottles ignited a fatal fire at a Swiss ski resort when they came too close to the ceiling of a bar crowded with New Year's Eve revellers.

Authorities planned to look into whether sound-dampening material on the ceiling conformed with regulations and whether the candles, which give off a stream of upward-shooting sparks, were permitted for use in the bar.

Forty people were killed and another 119 injured in the blaze early on Thursday as it ripped through the busy Le Constellation bar at the ski resort of Crans-Montana, authorities said.

Officials said they would also look at other safety measures on the premises, including fire extinguishers and escape routes. The attorney general for the Valais region warned of possible prosecutions if any criminal liability is found.

The injured included 71 Swiss nationals, 14 French and 11 Italians, along with citizens of Serbia, Bosnia-Herzegovina, Luxembourg, Belgium, Portugal and Poland, according to Frédéric Gisler, police commander of the Valais region. The nationalities of 14 people were unclear. (AP)