LONDON: Hundreds of passengers were evacuated from a Eurotunnel train under the Channel between Britain and France after a technical problem, its operators said on Tuesday.

Getlink, which runs the rail link between Coquelles in northern France and Folkestone in southeast England, said some 400 people had to abandon their vehicles on Tuesday.

An alarm on board forced crowds of people to have to leave the train for the adjoining concrete service tunnel, which is normally used by maintenance workers.

One passenger, Sarah Fellows, 37, called the experience "terrifying".

"There was a woman crying in the tunnel, another woman having a panic attack who was travelling alone."

Another traveller, Michael Kent, said passengers spent several hours in the train before it was evacuated as staff tried to solve the problem.

Passengers said they were eventually transferred to a replacement train but spent almost five hours in the undersea tunnel.

The incident affected a train leaving Calais at 3:50 pm (1450 GMT) on Tuesday, Later trains from France were delayed by up to six hours.

John Keefe, from operators Getlink, said passengers were taken to Folkestone while the original shuttle was brought out and they rejoined their vehicles.

"Operations like this do take time, but they are for the safety of everyone and must be conducted carefully," he told AFP.

By 6:00 am Wednesday, "everyone who was caught up in the incident had been carried across, diversions removed, and we are now back to normal services", he added.

The Channel Tunnel opened in 1994 and is composed of two single-track tunnels and a service tunnel each 50 kilometres (31 miles) long.

The undersea section covers 38km and is the longest in the world.

Since opening, it has carried more than 80 million vehicles on shuttle trains that are nearly 800 metres long.

Last month, Eurotunnel reduced the number of trains through the Channel Tunnel due to the effects of nationwide rail strikes in Britain, although its staff did not join the protest.