Passengers at Heathrow airport have been warned a “technical issue” affecting lighting on the runways could affect their journeys.
The airport said it was trying to fix the problem, but advised travellers to check their flight status with their airline before coming to the airport.
Earlier passengers due to fly into Heathrow had been reporting that they hadn’t been allowed to take off.
Flights have since been landing at the airport this morning.
British Airways initially warned it was diverting some flights but it now says contingency plans have been activated and it expects to operate a full schedule – with some delays.