Eurostar suspended train services in Europe on Tuesday after a power supply issue in the Channel tunnel, sparking travel chaos during the very busy travel season between Christmas and New Year.

Passengers were left scrambling to find alternatives after the operator postponed all services between London, Paris, Amsterdam and Brussels.

"There was a power supply problem in the Channel tunnel, followed by a shuttle train coming to a halt inside," a Eurostar spokesperson said.

"All journeys to and from London are suspended until further notice."

Eurostar's site showed that even its services on the Continent not using the Channel tunnel – such as ones between Paris and Brussels – were also cancelled.

Crowds of stranded travellers, many with suitcases, swelled at London's St Pancras station and at Gare du Nord in Paris as the notification went out that their end-of-year holiday plans were being thrown into doubt.

"I'm disappointed. We were going to do New Year's Eve in Paris," Jessica, a 21-year-old business coordinator looking to travel to France with three friends, said.

"We are going to see if we can find another ticket. Otherwise we will stay in London."

Jodie, who also declined to give her surname, had an AirBnB booked in the French capital until January 4 for her husband and four-year-old daughter.

"We can't find tickets for tomorrow. It has disrupted all our holiday. We are looking for alternative routes," the 37-year-old said.

The Channel tunnel's operator Getlink said train traffic would progressively resume Tuesday afternoon, but passengers were still left not knowing when, or if, they would travel.

One, Sophie Gontowicz, trying to head back to Paris after three days holidaying in the British capital with her family, said she was taking the disruption "philosophically".

"In the end, it gives us an extra day of vacation," she said.

Earlier, Eurostar had advised passengers to postpone their journeys citing "major disruption" caused by the power problem in the tunnel and "a subsequent failed Le Shuttle train".

"Please don't come to the station unless you already have a ticket to travel. We regret that trains that can run are subject to severe delays and last-minute cancellations," it added.

A record-high 19.5 million passengers travelled on Eurostar last year, up nearly five percent on 2023, driven by demand from visitors to the Olympics and Paralympics in Paris.

Eurostar has held a monopoly on passenger services through the tunnel linking Britain and France since it opened in 1994.

But British entrepreneur Richard Branson – the man behind the Virgin airline – has vowed to launch a rival service.

Italy's Trenitalia has also said it intends to compete with Eurostar on the Paris-London route by 2029.

Tuesday's disruption was the latest to affect Eurostar at a time when the company has faced criticism over its high prices, especially on the Paris-London route.

An electrical fault fault forced the cancellation of Eurostar services and severe delays on others in August.

The theft of cables on train tracks in northern France caused two days of problems in June.

LeShuttle operates vehicle-carrying trains between Folkestone in southeast England and Calais in northern France. (AFP)