Luton Airport has said a technical issue with Air Traffic Control has delayed departures this morning, while fog affected flights in and out of other UK airports.
Arrivals into Luton have operated normally, according to the airport, but departures have been delayed by up to three hours.
In a tweet, Luton Airport said: "Air Traffic Control experiencing weather related issues which are affecting departures."
Heathrow and London City airports warned flights could be affected by the fog and there are reports some Heathrow passengers were delayed for up to two hours.
Heathrow flights to Dubai, Madrid, Cologne, Newcastle, Ireland, Scotland and the US were delayed this morning.
At London City airport, flights to Amsterdam, Antwerp, Guernsey and Edinburgh were cancelled and others to Europe and the Isle of Man were delayed, according to the London Evening Standard.
Heathrow tweeted: "Foggy weather may affect scheduled flights today. Please kindly check your flight status with your airline."
City Airport said: "Due to earlier foggy weather conditions flights may be subject to delays, passengers are advised to check with airline for flight info."
At Gatwick airport, passengers reported one plane had got ‘stuck on the grass’.
Passenger Sophie Thirlwell, who was on the plane, said: "They can’t get the plane off the grass so we are all getting off and going back into the terminal."
