It added that "officers based at Heathrow are now investigating", along with colleagues from the airport.
"We are responding to a drone sighting at Heathrow and are working closely with the Met Police to prevent any threat to operational safety", the airport's Twitter account said. "They've only given us one update to say it was because of drone activity in departures".
Ministers are now exploring the use of military grade jammers and blocking systems to bring down rogue drones, such as the Israeli Drone Dome system reported to have been deployed at Gatwick.
'We apologise to passengers for any inconvenience this may cause'.
Flights at Heathrow Airport have been grounded after fresh reports of a drone sighting, with passengers venting their frustration on social media.
Arriving planes are continuing to land at Heathrow.
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It comes just weeks after drone sightings at Gatwick grounded planes for several days over the Christmas period. About 1,000 flights were cancelled or diverted, affecting 140,000 passengers.
Emma Gilthorpe, Heathrow's executive director for expansion, said the airport was committed to delivering the third runway scheme responsibly and urged local residents to have their say.
Today, the British government announced a package of measures created to give police extra powers to combat drones.
Gatwick has since said it has invested in anti-drone technology, while Heathrow said that it would do so.
The exclusion zone around airports will be extended to approximately a three-mile radius, with extensions from runway ends.
The government also announced from November, operators of drones weighing between 250g and 20kg would be required to register and take an online drone pilot competency test.