Snow strands Christmas travellers across north Europe

Snow and ice have stranded tens of thousands of would-be travellers across northern Europe.

The UK, France and Germany are among the worst-hit areas, with forecasters warning freezing weather may continue.

Hundreds of passengers desperate to return home for Christmas camped overnight at the world's busiest transport hub, London's Heathrow.

More than 1,000 flights were cancelled at German airports in Frankfurt, Munich and Berlin.

In France, Paris' Charles de Gaulle airport had three of its four runways open though most of the short-haul flights had been cancelled to enable longer-haul passengers to fly. 

At the capital's smaller Orly airport, although both runways were in operation, many flights had delays of more than three hours, according to French newspaper Le Monde. 

In Germany, airlines encouraged their passengers to take the train while train operators - whose services are already overcrowded - urged passengers to stay at home, Reuters reports.

At Frankfurt airport - where many spent the night on camp-beds - authorities brought in four brightly coloured clowns to try and lift the mood in the terminals.

But some of the most dramatic scenes took place in the British capital where, more than 48 hours after the last heavy snowfall in London, angry passengers with tickets turned up at Heathrow airport only to be turned away from the already overcrowded hub.

All short-haul flights had been cancelled and only one runway was in operation for the few flights that managed to take leave.

Backlog

The airport operator said that no more than one third of scheduled flights would be allowed to leave or land at the airport until at least 0600GMT on Wednesday.

Officials warned that despite relaxation of night-flight operations in an effort to loosen the backlog it might take until after Christmas to do so, and perhaps longer if more snow falls.

London's St Pancras International rail terminal was clogged with passengers and their luggage

The chaos at Heathrow had a knock-on effect in other international hubs where stranded passengers began to accept the possibility of not being with their loved ones over the Christmas period.

"My daughter is coming home and I don't see her very often and she's coming home to an empty house and it's just devastating," said 64-year-old Vivian Crosby, of Cambridge, England, stranded at New Jersey's Newark airport. 

Long queues

Others expressed disbelief that such a short burst of snow could have such a great impact.

Scott Kirker, from Philadelphia, had hoped to travel to Singapore via London to see his parents for Christmas but his flight was cancelled.

"We keep being told that London never has snow, it's never a problem! It's a major inconvenience for a lot of people," he said from Newark. 

Travellers' frustration was summed up by London Mayor Boris Johnson: "It can't be beyond the wit of man surely to find the shovels, the diggers, the snowploughs or whatever it takes to clear the snow out from under the planes, to get the planes moving and to have more than one runway going," he said late on Monday.

Airport operators explained that the sheer volume of snow - five inches in just one hour on Saturday - led to extensive ice buildup around aircraft on the ground and that safety concerns remained their priority. 

The treacherous conditions are costing British Airways some £65m (£100m; 75m euros) a day, analysts say, and the weather is severely impacting UK business in general: the number of customers in UK shops is down 25% at what is normally one of the most intense shopping periods of the year. 

There were severe delays on the Eurostar rail service between the UK and France and Belgium, and Thalys trains between France and Belgium were also affected as speed restrictions hit rail travel in England and northern France.

Lines of delayed passengers snaked for several hundred metres outside London's St Pancras station, and Eurostar - which has been turning away even those with bookings - urged travellers to cancel or postpone their trips if possible.

Main European airports and travel disruption

UK: British Airways cancels all short-haul departures. Heathrow, Gatwick, Cardiff, Edinburgh and other airports suffering disruption or knock-on effects

France: Authorities ask airlines to cut 30% of flights from Paris's two main airports Charles de Gaulle and Orly to ease congestion

Germany: Some 300 of 1,340 flights cancelled at Frankfurt because of problems elsewhere in Europe, airport operator Fraport says

Netherlands: The schedule at Schiphol Airport near Amsterdam is suffering cancellations and delays

German rail services were also affected. Heavy snow in Berlin caused problems for commuter trains and on the roads. Dangerous conditions were also reported on roads near Cologne.

Dutch authorities imposed a 50km/h (30mph) speed limit on a number of motorways, while 

icy, snowy roads also caused traffic problems across Sweden. 

As a sign of how bad conditions were, even in Moscow, where 9,000 snow ploughs were in action, some roads were at a virtual standstill.