Three people have died and several others have been badly injured after an avalanche hit a group of school pupils skiing in the French Alps.

Two of the deceased were teenagers, including a 14-year-old boy, while the body of a Ukrainian skier was also found by rescue teams.

Among the injured, two pupils were said to have suffered cardiac arrest while another was described as seriously hurt. Search teams are looking for at least five youngsters but some reports said the number of missing could be as high as 20 although all members of a school group from Lyon have been accounted for by rescue teams.

The avalanche took place on piste at the ski resort Les Deux Alpes, in Bellecombe, Isère, eastern France.

Police told French media two pupils were found in a state of cardiac arrest and their teacher unconscious. The children were reported to have been skiing on a black-rated run - the highest difficulty rating - which had been closed at the resort because of heavy snow.

French President Francois Holland offered his "sincere condolences" to the victims' families, saying that the "solidarity of the whole nation" was with them. France's Education Minister Najat Vallaud-Belkacem will visit Lyon on Wednesday (13 January) evening.

Earlier authorities had warned winter holidaymakers the risks of even "spontaneous" avalanches remains "high" due to the warm December weather. Four people have died as a result of avalanches in the French Alps this month already.

On 5 January, a 30-year-old skier from the Czech Republic was also killed at Saint-Colomban-des-Villards after going off piste in the Les Sybelles area. Two days earlier, on 3 January, an avalanche near the Chamonix resort saw two Lithuanian mountain climbers also killed.

The avalanche risk for several resorts in the Alps remains at four out of five, which means avalanches are "likely to be triggered on many slopes even if only light loads are applied". It also means medium or large "spontaneous" avalanches are likely.

It has led some tourist boards, like the one at Val d'Isere, to warn skiers not to go off piste. Anyone planning a trip to the Alps is also advised check the snow report for the resort (often found on its website), or visit the Meteo France website.