A British woman and her son have died after an avalanche swept through an off-piste area of a French ski resort.

The Foreign, Commonwealth and Development Office (FCDO) confirmed it was supporting the family of two Britons who died.

The 54-year-old mother and her 22-year-old son had been skiing with other family members, according to the Bonneville public prosecutor’s office.

We are supporting the family of two British people who died in France and are in contact with the local authorities

Another skier, reportedly an instructor, has been left injured and a hiker was killed in a separate area after the avalanche on Mont Blanc.

An FCDO spokesperson said: “We are supporting the family of two British people who died in France and are in contact with the local authorities.”

The avalanche hurtled through an off-piste section of the Saint-Gervais-les-Bains ski resort on Thursday, according to the administration for the Haute-Savoie region.

A search-and-rescue effort was deployed, including around 20 rescuers, two dog teams, a doctor and two helicopters, lasting around five hours.

The avalanche may have been caused by cross-country skiers who were uphill, the Bonneville public prosecutor’s office said.

A family is decimated, and we are very sad in Saint-Gervais

It added that a manslaughter investigation has been opened by police in Chamonix and that post-mortem examinations will take place in the coming days at the medical-legal institute in Grenoble.

The Associated Press (AP) reported that Saint-Gervais mayor Jean-Marc Peillex called weather conditions too unstable for such outings.

He told BFM television: “It rained, it snowed, it was warm. There are enough marked paths to ski on.

“It’s terrible what happened. A family is decimated, and we are very sad in Saint-Gervais.”

A 31-year-old hiker was found dead after falling on the slope of the Ecrins mountain range, AP reported.

According to the news agency, local broadcaster France-Bleu said rescuers explained the hiker had stepped away from hiking paths to look at mountain goats.