Heavy fog across the south of the UK has resulted in the cancellation of 100 flights from Heathrow Airport .
The London airport, the busiest in Europe, said 100 of the 1,300 flights expected on Monday would be cancelled because of low visibility.
"Heathrow's top priority is the safety of passengers and we apologise to those whose travel has been affected," said an airport statement, adding that passengers should contact their airlines before arriving.
London City Airport, located near the centre of the British capital, was also forced to ground several flights, but did not report the number of affected planes.
Stansted Airport, to the north of the city, said no flights had yet been cancelled but asked passengers to speak to their airlines as a precaution, while Gatwick, to the south, did not report any cancellations or delays.
