Dec 21 - Northern Europe's big freeze wreaked more havoc with flights on Tuesday as airports struggled to cope and retailers fretted they would struggle to make up lost sales in the few shopping days left before Christmas.

A passenger sleeps in the hall of an airport temporarily closed because of heavy snowfall

More planes got off the ground than on Monday but for thousands of travellers hoping to get home or away for Christmas, delays and cancellations were widespread.

Eurocontrol, which oversees air-traffic control across 38 countries, said it expected more services to operate after about 3,000 flights across Europe were cancelled on Monday.

Europe's weather woes are having far reaching implications, with Kenya warning it was likely to miss its 2010 tourism forecasts as a result of the flight disruption.

With more snow forecast, there was little Christmas cheer for those camped at London's Heathrow Airport waiting for flights or queuing for cross-channel Eurostar trains in sub-zero temperatures outside central London's St. Pancras station.

And with airlines feeling the growing cost of the chaos, Europe's transport chief said he was considering forcing airports to provide them with a minimum level of infrastructure support during such severe weather.

"I have become increasingly concerned about the problems relating to the infrastructure available to airlines -- airports and ground handling -- during this severe period of snow," European Union transport commissioner Siim Kallas said.

By Rhys Jones and James Davey