A judge in Switzerland has ordered that one of the two co-owners of the ski resort bar where 40 people died in a fire on New Year's Eve be kept in detention for 90 days.

Swiss prosecutors have argued that Jacques Moretti, a French national, is a potential flight risk. He and his wife Jessica, who is also French, are suspected of manslaughter by negligence, bodily harm by negligence, and arson by negligence.

The blaze at Le Constellation bar in Crans-Montana also left 116 people injured, many of whom were aged under 20.

Authorities acknowledged last week that the bar had not undergone safety checks for five years, prompting outrage from victims' families.

Moretti was first detained on Friday for an initial 48-hour period, but the judge extended his detention citing a potential flight risk and the seriousness of the allegations. The fire reportedly started when celebratory sparklers were raised too close to the ceiling.

In light of the incident, local authorities have vowed to enforce stricter safety provisions in the future, including banning sparklers in venues like Le Constellation.