LONDON -- London's Heathrow Airport canceled a fifth of flights and airlines scrapped 40 percent of flights to Paris' main airports as snow continued to blanket parts of Europe, with more forecast.

Air France predicted more cancellations on a similar scale for Monday.

Heathrow Ltd, which is owned by Spain's Ferrovial, said the reduced schedule -- amounting to about 250 fewer flights -- would help it cope with the expected snowfall without making further cancellations.

As snow continued to fall through Sunday, the airport operator said Monday's flight schedule would be cut by 10 percent. That number could rise, depending on conditions at other European airports, Heathrow said.

The Paris airport operator, ADP, said airlines scrapped 40 percent of flights into and out of the two main airports on the outskirts of Paris, Charles de Gaulle and Orly, primarily reducing short-haul services. 

London's smaller Stansted and Gatwick airports said they were operating as normal on Sunday morning but that delays and some flight cancellations were likely. 

Weather forecaster the British Met Office said snow was likely to continue into Monday. As much as eight centimeters was expected in southeast England on Sunday, it said.

On average, some 1,300 flights leave Heathrow daily. The airport, Europe's busiest, operates at close to full capacity after Britain's coalition government blocked development of a third runway in 2010. 

Heathrow has spent 36 million pounds ($57 million) on upgrading its winter weather equipment since 2010 -- a year that saw it face heavy criticism after it almost shut down when snow hit just before Christmas. It now has 130 snow-clearing vehicles. 

More than 400 flights were canceled on Friday, while on Saturday 111 flights, most of them operated by IAG's British Airways, were canceled and hundreds of passengers spent the night in Heathrow's terminals. 

Watch World News videos on NBCNews.com

BA said there had been a knock-on effect because many of its planes were in the wrong place after Friday's snow.

"Like other airlines at Heathrow we have complied with a request to reduce our schedule by 20 percent on Sunday and we continue to work with Heathrow Airport to help keep the airport running as smoothly as possible," BA said in a statement. 

"We are doing everything we can to help customers whose flights have been disrupted by severe weather."

PhotoBlog: Hundreds of flights canceled at Heathrow due to snow

Services by Air France-KLM, Ireland's Aer Lingus and Germany's Lufthansa have also been affected. 

France's SNCF railway company announced delays of up to 40 minutes on many lines as drivers were ordered to reduce speed as a safety measure. 

Local media said some 25,000 homes lost power in southwestern France. 

($1 = 0.6304 British pounds)

Additional reporting by Rosalba O'Brien in London, and Brian Love and Gerard Bon in Paris.