Image copyright AFP/Getty Images Image caption Fog is covering the south-east of England and parts of Europe

Flights have been cancelled at the UK's two biggest airports because of freezing fog.

Easyjet said on Friday it had cancelled 56 flights at Gatwick airport, which has drafted in extra staff and ground handlers to keep people moving.

Heathrow said more than 100 flights had been cancelled.

A spokesman for Gatwick said dense fog had caused delays and cancellations and apologised for the "unavoidable and unfortunate disruption".

'Check before travelling'

He said air traffic control restrictions had been imposed because of the heavy fog over south-east England and parts of Europe, where many aircraft were headed.

"Passengers are strongly advised to check with their airline as to the status of their flight before travelling if possible," he added.

Heathrow told the BBC 119 flights had been cancelled and more may be cancelled later.

London City airport said about 26 flights had been diverted, and more than 60 arriving and 70 departing flights had been cancelled.

Easyjet said all airlines had been advised by Gatwick to cancel some flights.

An airline spokesman said: "While these circumstances are outside of the airline's control, Easyjet apologises for any inconvenience caused and would like to reassure passengers that we are doing everything possible to minimise the disruption."

The National Air Traffic Control Service (Nats) said the fog had caused disruption because greater spacing was required between aircraft to ensure safety when visibility was poor.

A spokesman for Nats said: "We are working closely with our airline and airport customers to minimise disruption to their operations."