London's Heathrow, Europe's busiest airport, cancelled half its regular number of flights on Sunday as European countries coped with an unusually heavy snowfall and freezing temperatures.

The airport normally has around 1,300 flights a day, but officials cut the schedule after up to 16 centimetres of snow fell across much of Britain.

They said Heathrow should return to a full flight schedule on Monday. The airport is used by about 180,000 people daily. Dozens of flights have also been delayed or cancelled at Amsterdam's Schiphol Airport.

Britain's national weather service issued an "amber" weather alert, warning of sub-zero temperatures and heavy snow, which snarled roads and railways.

"It's not a huge amount, granted, but it has caused problems, particularly in terms of transport. There have been reports of car accidents and we heard how 100 vehicles were stranded in one stretch of motorway and some had to spend the night in their cars as a result," journalist Dominic Valitis reported from London.

"It's likely that tens of thousands will be affected over the coming days," as rain and sleet will take the place of snow in the U.K., Valitis said.

Forecasters said the temperature in Paris would be colder than in Winnipeg on Sunday. They predicted it would be -3 C in the French capital, while people in the Manitoba capital would enjoy a relatively balmy 3 C. Temperatures were -6 C in other parts of France.

Snow also has fallen on Spain's Balearic islands in the Mediterranean.

While Western Europe struggles with a blast of winter, the effects were mild compared with what Eastern Europeans are suffering.

Eastern Europe suffers cold snap

Across the region, thousands of people have been digging out from heavy snow that followed a weeklong cold snap, blamed for killing more than 260.

Bosnian authorities on Sunday used helicopters to evacuate sick people and deliver food to thousands of people who have been cut off by the heaviest snow the country has ever recorded.

Bosnian Merim Muslibegovic, 41, left, and his daughters Senka, 15, and Sara,7, shovel snow in Sarajevo on Saturday. (Amel Emric/Associated Press)

More than 100 remote Bosnian villages are cut off by snow over two metres high in the mountains. More than a metre has fallen in the capital Sarajevo, where a state of emergency has been declared.

Three helicopters cruised over eastern Bosnia Sunday, delivering food and picking up people who needed evacuation.

Sarajevo has been paralyzed since Friday evening, blanketed by a metre of snow, and authorities have ordered all schools closed. Residents have volunteered to remove snow and ice from the trams that are stuck along the city's tracks.

In neighbouring Serbia, officials said 70,000 people remain cut off.

So far, 32 municipalities throughout the country have introduced emergency measures, said senior emergency official Predrag Maric.

Ukraine has been hardest hit by temperatures as low as -38 C, with at least 131 deaths over the past week, most of them homeless people. The Ukraine Emergencies Ministry said about 2,300 people were receiving hospital treatment for cold-related ailments such as frostbite or hypothermia.

Deaths from the cold have also been reported in Poland and Romania.

With files from The Associated Press