London's Heathrow Airport says flight departures have been suspended as a precaution after a reported drone sighting.
The airport has tweeted out saying they are closely working with local police to prevent any threat to safety.
Airport officials say they are working closely with police to clarify the situation.
The report follows the pre-Christmas shutdown of London's Gatwick Airport for parts of three consecutive days due to reported drone sightings.
UK correspondent Gavin Grey told Tim Dower passengers in the planes grounded on the tarmac are taking to social media.
"There are lots of vehicles on the runway looking up at the skies, along with security who are looking to find out what is happening."
The Gatwick closure led to more than 100,000 people being stranded or delayed, the worst ever drone-related disruption at an international airport.
LISTEN ABOVE AS GAVIN GREY SPEAKS TO TIM DOWER