London's Heathrow Airport on Saturday cancelled 30 percent of Sunday's flights as it braced for heavy snow and freezing fog.      

The airport, which is expecting up to 15 centimetres (six inches) of snow overnight, said it would publish a list of the flights it will operate on its website at 6pm (1800GMT) Saturday, but warned further cancellations were possible.

"We expect the percentage of passengers who are able to fly to be higher than 70 percent as airlines will transfer people between flights," the airport said in a statement on its website.

"Passengers should contact their airline for more information."

The west London airport, which is the world's busiest in terms of international passenger traffic, said it expected snow at Heathrow from 5pm (1700 GMT) on Saturday until 6 am on Sunday, with up to 15 centimetres to fall in total.

Officials at the airport, which handles more than 180,000 passengers a day, also warned of reduced visibility and possible freezing fog from 1800 GMT.

Heathrow's chief operating officer said the cancellations would ensure that "the greatest number of passengers can fly with the minimum amount of disruption."

"It also means that those passengers whose flights are cancelled will know in advance, and can make alternative arrangements or rebook in relative comfort," Normand Boivin said.

Britain's Met Office forecaster issued its second highest severe weather warning on Saturday, with swathes of the country expecting heavy snow and travel disruption.

Northern, central and eastern England are expecting up to 15 centimetres of snow. Light flurries began falling on the city of Manchester, northwest England, around midday.