Last Updated 3:42 p.m. ET
The only passenger rail link between Britain and the rest of Europe has been shut down indefinitely, Eurostar said Sunday, promising more travel misery for thousands of stranded passengers just before Christmas.
Services have been suspended since late Friday, when a series of glitches stranded five trains inside the Channel Tunnel and trapped more than 2,000 passengers for hours in stuffy and claustrophobic conditions.
Some panicked passengers stayed underground for more than 15 hours without food or water, or any clear idea of what was going on prompting outrage from travelers and a promise from Eurostar that no train would enter the tunnel until the issue had been identified and fixed.
Eurostar runs services between England, France and Belgium. The company said Sunday it had traced the problem to "acute weather conditions in northern France," which has seen its worst winter weather in years.
The company did not go into details, but in a statement it said its program to prepare Eurostar trains for winter conditions had not been adequate and that engineers had to "further enhance the snow screens and snow shields in the power cars of the trains."
The statement said the fleet was already undergoing upgrades and that more tests were planned for Monday. A Eurostar spokeswoman said she could not guarantee that service would resume Tuesday.
The stoppage has already meant that about 31,000 people in Britain, France and Belgium have had to cancel trips Saturday, and 26,000 more were expected to be affected Sunday. With a huge backlog of passengers still building, Eurostar has blocked any sales until after Christmas and Brown warned that services may not be back to normal for days.
For those seeking alternative routes between Paris, Brussels and London, the winter weather was dealing out more bad news.
Nearly half of all flights out of Paris' Charles de Gaulle and Orly airports were cut Sunday through mid-afternoon, with more cancellations forecast for Monday. Belgium was also badly hit, with passengers in Brussels lining up for hours in an effort to rebook flights.
Tourist Paul Dunn, 46, who was stuck in Paris, said he was looking for alternatives but that information was hard to come by.
"We said: 'Can we get the train to (the French city of) Calais and the ferry?' They are saying: 'We don't know what you can do. You can try.'"
It is a measure of the popularity of the 15-year-old Eurostar service which whisks passengers from London to Paris or Brussels in about two hours that its closure has dominated news in Britain.
European parliamentarians on both sides of the Channel have criticized the train company as being irresponsible, while Britain's opposition Conservative Party said the issue was a matter of "huge concern."
Eurostar originally said that four of its trains were halted in the tunnel Friday evening. On Sunday the company said a fifth train had also been disabled in tunnel before being towed to London. A sixth train broke down Friday, although outside the tunnel, 24 miles of which sits under the English Channel, Eurostar said.
Following unsuccessful attempts to move some passengers between London and Paris Saturday evening, the company has canceled all services "until we get to the bottom of what happened Friday night," Eurostar chief executive Richard Brown said. "We will not start services again until we are sure we can get them through safely," he told BBC television. "We want to understand what it was that caused this unprecedented breakdown."
The company said it had taken the precautionary step of canceling all ticket sales until after Christmas.
Accounts from trapped passengers spoke of languishing in the dark for up to 16 hours without adequate food, water or any clear idea of what was happening. Some reportedly suffered asthma and panic attacks.
While most of the trains were towed out, two had to be evacuated, forcing passengers to walk through sections of the darkened tunnel.
Brown seemed to acknowledge that there were some problems on at least one train but defended his staff.
"I'm not pretending it well. I think it went quite a bit better than people say," he said.
Earlier, officials blamed the problems on the quick transition from the icy cold of France, which is suffering some of its worst winter weather in years, to the relative warmth of the tunnel, which could have produced condensation and interfered with the trains' electrical systems. But the exact cause remains unclear.
"It's all a bit of a mystery and the company, and indeed a lot of people, appear baffled by it," said Nigel Harris, the managing editor of Rail magazine. "What is really puzzling about this is the fact that it is happening now, even though the trains have been exposed to cold weather over the last few years."
Comparable trains in France have "been going even longer than Eurostar without experiencing any of these cold-weather problems," he said. The cold weather has had little effect on France's TGV high speed trains, some of which were running with minor delays Sunday because of drivers slowing down on certain sections of track.
At London's St. Pancras Station, television footage showed bleary-eyed passengers waiting in line or scrambling for information about Eurostar. A few were in tears.
The problems - and passengers' complaints about their treatment while trapped on board - could deal Eurostar "huge reputational damage," Harris said. "They have promoted themselves as the 'green,' stress-free alternative to flying and now they face a major technical issue that they need to get on top of."
Eurostar's reputation for safe operation already suffered a setback in September 2008, after a fire broke out as one of the trains entered the 30 mile tunnel. Service was pared back for five months as extensive damage was repaired.
Eurostar's executives have offered refunds and free travel to those affected by the latest cancellations.