One person died and more than 40 were injured when an Alpine tourist train derailed in Switzerland today.

The accident was on the Glacier Express route through the spectacular scenery of the Swiss Alps between the towns of Zermatt and St. Moritz.

Police said six of the injured were in serious condition and most of the passengers were tourists, many of them Japanese.

Two of the carriages left the tracks and a third tipped over.

Rail delays, let alone accidents, are rare in Switzerland. The Glacier Express - dubbed the "slowest express train in the world" - is known as much for its majestic mountain climbs as for its pedestrian 18 mph average speed.

The three cars were at the back of the train and the derailment took place near the town of Fiesch and the mouth of the Aletsch glacier, Europe's largest icemass.

Rail traffic remained closed near the accident site tonight and local police were investigating.

The 80-year-old Glacier Express runs several times a day all year round, carrying some 250,000 passengers a year.

It starts in Zermatt, at the base of the Matterhorn and rumbles through terrain over a mile above sea level, surrounded by many of the highest Alpine peaks.

After 7 1/2 hours, 291 bridges and 91 tunnels, it ends in St. Moritz. Carriages have special large windows that sweep high onto the roof so tourists can take in the mountain vistas.

A celebration of Swiss engineering, the Glacier Express offers breathtaking views of mountains, glaciers, viaducts across rushing streams and switchback rail lines that sometimes go in full circles to spiral up or down the steepest slopes.

The accident was the country's worst rail mishap since 2006, when three men died after a runaway train travelled for miles without brakes before crashing into another train.