The airport flagged the outage in a tweet shortly after 4.30am and advised passengers to check the status of their flight before travelling.

It is understood the issue affected both inbound and outbound flights, with passengers at other airports around the world taking to social media to report delays to their departures.

Heathrow confirmed the problem had been fixed in a tweet issued at 6.04am and that both runways were “open and operational”.

However, the airport said it was continuing to monitor the situation and again urged passengers to check the status of their flight before attempting to make any journeys.

British Airways said a number of flights were diverted away from the airport during the runway closure, adding it had since enacted contingency plans to minimise further disruption.

The airline added it expects to operate a full schedule, albeit with delays.

The Guardian, citing aviation data firm FlightStats, reported 16 inbound flights had been, or were likely, to be affected. One outbound flight was cancelled and two delayed.

Heathrow’s initial tweet read: We’re currently investigating and working to fix a technical issue with the lighting system for the runways. Please check your flight status with your airline before travelling to the airport. We’re sorry for the impact this will have on our passengers.”

It later added: “Following earlier runway lighting issues both runways are now open and operational. While we’re continuing to monitor the situation, please check your flight status with your airlines before travelling. We apologise for the disruption to your journey.”