Thousands of passengers were stranded on Sunday after heavy snow and forecasts of freezing fog forced London Heathrow Airport to cancel 50 percent of its scheduled flights.

"Airlines expect to operate about 50 percent of the 1,300 flights originally scheduled for today," the west London airport said in a statement on its website.

Six centimetres (2.4 inches) of snow blanketed Heathrow overnight, but the announcement came as the flakes stopped falling over Britain and as forecasters predicted a partial thaw.

"Our runways, taxiways and stands have been cleared of snow," said Heathrow. "The airport is getting back to normal. However there will still be disruption for passengers as indicated yesterday."

Officials had not reduced the flight schedule for Monday but warned there could be further cancellations as a result of the earlier disruption.

The airport, which is the world's busiest air hub in terms of international passenger traffic, said it expected no further snowfall on Sunday but said freezing fog was forecast from 6:00pm (1800 GMT).

The airport's decision to cancel thirty percent of Sunday's flights on Saturday, before any snow had fallen, was met with derision in the British press.

"27C in Munich, but still every plane flies," said the Mail on Sunday. "Meanwhile, despite 32 million pounds on new snowploughs, Heathrow cancels flights BEFORE a flake of snow falls.

"Whatever the explanation, Heathrow's defeatist performance is not worthy of a world-class transport hub," the tabloid concluded.

Heathrow, which handles more than 180,000 travellers a day, defended the decision by saying it gave passengers better information about whether they would be able to fly or not.

"By cancelling flights in advance airlines have been able to rebook some people onto flights that are departing," it said, adding that its "snow plan" had worked "far better" than in previous years.

Heathrow came under heavy criticism in December 2010 after snow led to the virtual shutdown of the airport for several days.

Other British airports affected by the freeze include Stansted, Manchester, Birmingham and Luton, which ground to a halt for part of Saturday night after snow blocked the runways. Operations resumed on Sunday with some delays.