The Eurostar service between London St Pancras International and Paris is the latest casualty in the transport carnage over the busiest weekend of the year.
A problem with the power supply at Paris Gare du Nord is severely disrupting services.
The train operator has cancelled two trains each way to and from the French capital, on one of the busiest days of the year.
British Transport Police are assisting at the Eurostar terminal as hundreds of passengers attempt to rebook.
The train operator said: “Due to an overhead power issue in Paris, our traffic to and from Paris is severely disrupted and we advise passengers to travel only if essential.
“If you choose to travel, please proceed to ticket gates at the time indicated on your ticket as normal.
“If you arrive at your destination more than 60 minutes late, you can claim compensation.”
With the transport system being stretched to capacity, there are few alternatives. British Airways has cancelled multiple flights between Heathrow and Paris Charles de Gaulle as weather-related delays increase at the UK’s busiest airport.
Links to and from Brussels are also encountering problems due to speed restrictions in Belgium because of the extreme temperatures.
Eurostar said: “Passengers travelling on that route today can postpone their journeys for free or ask for a refund.”
In response to a question from a traveller booked on Saturday, the train operator added: “We can only advise on keeping an eye on the website for updates.”
