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.

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. 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.