All Eurostar services have been suspended today (Monday December 21) and passengers are being warned they may not make it home in time for Christmas.
Eurostar is urging passengers whose travel is non-essential to change their dates of travel or seek a refund.
The train operating company blamed the disruption of “acute weather conditions” in Northern France.
The latest disruption follows events last week which left more than 2,000 passengers trapped overnight in the Chunnel.
Travellers were stranded for up to 15 hours on Friday night after four Eurostar trains broke down.
Many suffered panic attacks or fainted as they waited for help.
Unconfirmed reports suggest that fellow passenger German supermodel Claudia Schiffer was picked up by a car which drove to her carriage from the tunnel entrance.
Eurostar chief executive Richard Brown blamed the breakdown on the contrast between cold temperatures on the railways and a warm tunnel.
A statement from Eurostar reads:
As a result of the test runs that were conducted today we now understand the cause of the disruption over the weekend and have identified the modifications that are required.
“As we suspected, the acute weather conditions in northern France have caused the disruption.
“Every year we carry out a ‘winterisation’ programme of the entire fleet which to date has successfully protected our trains.
“We now know, however, that we need to further enhance the snow screens and snow shields in the power cars of the trains.
“We have already started making the modifications and to ensure that these new protection measures work effectively we are conducting a further series of test runs tomorrow.
“Our priority is ensuring that when we resume services we provide our customers with a robust and reliable operation.
“We sincerely regret having to take this decision and we understand how frustrated and disappointed travellers will be, particularly those who have been waiting to travel for the last two days.
“We strongly advise passengers whose travel is non-essential to change their booking to a later date or claim a refund on their tickets.
“For customers who have been unable to travel over the last few days, Eurostar will cover the cost of out-of pocket expenses, for example, hotels and taxis.
“Full details of our compensation policy are on www.eurostar.com.”