Tens of thousands of airline passengers flying in and out of airports in southern England are facing delays due to a reported air-traffic control radar failure at the Swanwick headquarters of the air-traffic provider, NATS.
The company said it is "restricting the number of aircraft flying across the south of England and those taking off from airports".
At Gatwick, some easyJet departures and arrivals were delayed by up to 90 minutes. BA's flight from Jersey to Gatwick was operating two hours late. When the problem first became apparent, Jersey airport issued a tweet that claimed: "Computer failure at National Air Traffic Control Centre at Swanwick has resulted in the temporary suspension of all flights in and out of UK air space".
In response NATS tweeted: "Important to note this issue has not closed UK airspace. Aircraft are still moving, but restrictions are in place to ensure safety.
Ryanair issued a statement saying: "We have been advised by UK National Air Traffic Services (NATS) of an ATC system failure which will cause significant delays and possible cancellations to flights operating to/from southern UK Airports and those overflying the UK."
British Airways, which operates more than half the flights at Heathrow, said it had not suffered any problems at the airport.