VIDEO: Alps rockslide halts train services between France and Italy

This videograb shows a spectacular rockslide in the Maurienne valley of the French Alps. AFP

Train services between France and Italy have been halted until Thursday at the earliest, after a huge rockslide in the Maurienne valley of the French Alps which also blocked some roads, officials said on Monday.

Regional authorities in Savoie said the rockslide occurred at 5:15pm on Sunday, when "boulders with a total volume of 700 cubic metres" slammed into a protective barrier along the RD 1006 road that leads to the Mont-Cenis pass into Italy's Susa valley.

The landslide forced the suspension of all cross-border trains on the Chambery-Turin line, as well as TER regional trains in the Maurienne valley, French rail operator SNCF said.

The Frejus tunnel connecting France and Italy under the Alps has also been closed to heavy trucks, whose drivers are being advised to use the Mont Blanc tunnel or the A8 motorway instead.

French Transport Minister Clement Beaune said a return to normal services "will require several days."

"After this massive landslide yesterday in Maurienne, our services are mobilised to restore road and rail service as quickly as possible," he said on social media.

Sunday's landslide followed "heavy rain with sizeable downhill flows, after a heatwave throughout the Alps," said Denis Roy, weather chief at Meteo France for the mountain region.

"There have always been rock falls, but there are periods more favourable than others, like this somewhat rare heatwave," said Serge Taboulot, president of the Institute for Major Risks in nearby Grenoble.

Images shared on social media showed a huge cloud of dust detaching from a cliff and plunging onto the local road that runs alongside the railway line and the motorway.

The RD 1006 road had luckily been closed half an hour before when a single block of stone fell, said Jean-Philippe Laplanche, infrastructure chief in the Savoie department.

Authorities are "very vigilant about this kind of incident", which have "been picking up due to climate change", he added.

Rail operator SNCF said that "access to the site is still forbidden because there is still a risk of rock falls".

Only when geologists arrive on the ground will the state-owned firm be able to evalute the damage and further risks, it added.

The ATMB company which runs the toll tunnel through Mont Blanc said queues had mounted to more than two hours on the French side and three on the Italian.

The last major geological event to disrupt rail traffic on the France-Italy line was a mudslide in 2019 that covered the track for 60 metres, halting traffic for three weeks.

Agence France-presse