After three days of cancellations, Eurostar has resumed a limited service between London and the Continent. But there were chaotic scenes at St Pancras this morning as thousands queued in subzero temperatures in the hope of catching the first high-speed trains out of the station since Friday.

About 3,000 customers were waiting at 5am, with some queuing overnight. The first train set off at 7.40am.

More than 55,000 people have been left stranded by a fault caused by snow melting in the Channel Tunnel shorting electrical circuits. Over 2,000 passengers were trapped on trains overnight in the tunnel on Friday.

Passengers protested at delays and a lack of information, while politicians both sides of the channel criticised the high-speed operator.

Last night the company offered its first explanation of the problem. Commercial director Nick Mercer said: “The amount of snow was higher than we experienced before, it was lighter than normal, fluffier.”

Chief operating officer Nicolas Petrovic said that dry, powdery snow unusual in northern France had been sucked into the trains’ engines, where it sparked a failure on the electrical circuit.

Eurostar is only offering a limited service for passengers who had tickets booked for the weekend, with many being told to return tomorrow.

It has also warned customers with tickets for Tuesday not to come to the station because they would not be guaranteed seats.

However, hundreds arrived with their luggage in the hope that they would be allowed on, only to be refused a seat after queuing for more than an hour.