Airline passenger baggage is left in Terminal 3 at Heathrow Airport in west London December 20, 2010. [Photo/Agencies]

BERLIN– Heavy snow and frigid temperatures caused further disruption across northern Europe on Monday -- stranding travelers, snarling traffic and shutting schools.

More than 1,000 flights at Germany's main airports in Frankfurt, Munich and Berlin were canceled and many more delayed after up to 40 cm (16 inches) of fresh snow blanketed the country. Some 500 stranded passengers slept on cots at Frankfurt airport.

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Airlines advised passengers to switch to trains if possible after the new snow added to two week's worth of accumulation but rail operator Deutsche Bahn, struggling to cope with packed trains and a crush of passengers, urged passengers to stay home.

Tempers flared as Germans accustomed to timely trains and planes were forced to wait in freezing stations or packed terminals, and the unusually heavy snow delayed millions of commuters. Meteorologists warned there was more snow to come.

"The trains are always too late now," said Lothar Ast, 57, a custodian shivering in a Berlin station. "They're so crowded that you can't get on and then you have to wait for another."

Dorothea Fuerst, a Berlin sales clerk, added: "No one knows if the train will come or not. The train never arrives on time. Will it be 15 minutes or half an hour? That's the question."

Children's sledges were sold out in Germany, retailers said.

"This much snow is only fun if you're a kid," said Berlin lawyer Katja-Julia Fischer, 42: "It's getting on my nerves."

Germany's most populous state, North-Rhine Westphalia, took the unusual step of banning trucks from motorways in a bid to keep passenger traffic rolling. A rail worker was killed in Berlin, run over by a train while trying to de-ice a switch.