A train carrying 200 passengers has been derailed by a landslide causing several carriages to plunge into a ravine in Switzerland.

Pictures from the scene showed at least one carriage in a ravine and another hanging precariously from the tracks winding through mountains in the east of the country.

Rescue helicopters were seen hovering over the train in the mountainous region of Graubuenden.

Scores of passengers on board the carriages which managed to remain upright scrambled to safety and could be seen standing at the side of the tracks.

A number of injured passengers were airlifted to hospital, while several others were treated for shock by paramedics.

"Part of the train was derailed by a landslide," a spokesman for Rhaetische Bahn said, but he was unable to give further details immediately.

The train was travelling from St Moritz to Chur when it was caught in the landslide between Tiefencastel and Solis, southeast of Zurich, at around 1:45pm.

Three carriages came off the tracks and plunged down the slope of the mountainous region after hours of rainfall in the area, earlier.

One eyewitness, who was travelling with his wife and granddaughter to Basel, told Swiss website Blick.ch they were sitting behind one of the carriages that plunged into the ravine which had passengers on board it.

"There was an announcement that we should move into the rear car," he said. Afterwards, all of those on board the train were told to get off it.

"We had to walk about a kilometre...through a tunnel. The luggage is still on the train."

Reports suggested there were no fatalities, but police said several passengers were injured.

Originally publsihed 14:36