Flights to and from UK airports are being cancelled and delayed by a computer problem at the main air traffic control centre at Swanwick, reported BBC.
All departures have been suspended from Luton airport due to air traffic control restrictions.
Arrivals are also subject to delays. Passengers are being advised to contact their airline before travelling.
Heathrow Airport is also reporting disruption on all flights due to technical problems.
The Control Flow Management Unit at Eurocontrol in Brussels confirmed that the London Area Control Centre (LACC), which covers the south east of England, has suffered a computer failure.
The LACC is still operating, but is restricting departures due to the additional workload.
BBC transport correspondent Tom Symonds said the problems stemmed from a glitch with computers which deal with information about flights when they are at higher-altitude.
Air traffic controllers could still see where planes were, but were finding it difficult to identify them, he said.
This had resulted in a reduced flow of aircraft from airports in the south east of England, with planes at Heathrow leaving every five minutes rather than every 90 seconds, he added.
British Airways says it is cancelling "a few" short haul flights to domestic and European destinations from Heathrow.
Airport authorities have advised passengers to contact their airlines before travelling.
