LONDON - Heavy fog caused the cancellation of scores of flights at London's two largest airports Sunday during the Christmas rush.

Heathrow Airport was the worst effected, with 129 incoming or outgoing flights cancelled, said BAA spokesman Stuart Butcher.

"Heathrow escaped the severe fog that had hampered other airports in the London area on Friday and Saturday, but it hit us today,'' he said.

Butcher said 69 of the airport's 650 scheduled departures were cancelled Sunday, and about 60 of the 650 scheduled arrivals. He said many of the cancellations involved short-haul or domestic British Airways flights.

He said the fog remained heavy at Heathrow at about 4 p.m. but that forecasters said it would lift later, opening the possibility that stranded passengers would be able to board other flights.

Butcher said Heathrow had served 214,000 passengers on incoming and outgoing flights Saturday, and about 181,000 were scheduled Sunday.

Gatwick Airport also was having problems with the fog Sunday, but was experiencing far fewer cancellations.

Karen Reeves, BAA's spokeswoman there, said 15 outgoing short-haul flights had been cancelled at Gatwick by the afternoon: 10 with BA and five with EasyJet. She said 700 flights are scheduled daily at Gatwick at this time of the year, the height of the Christmas travelling season.