Europe's busiest airport is shut down after a drone sighting

Heathrow Airport

London's Heathrow Airport.

• London's Heathrow Airport has suspended all flight departures after a drone was spotted on Tuesday evening.
• Last month, drones shut down London's Gatwick Aiport for 32 hours.
• A Heathrow spokesperson said the airport is working with London's Metropolitan Police Service "to prevent any threat to operational safety."
• London Heathrow is the busiest airport in Europe and the seventh busiest in the world handling more than 78 million passengers annually. 

London's Heathrow Airport has suspended all flight departures after a drone was spotted on Tuesday evening.

After reports on Twitter that a drone had kept flights grounded, a Heathrow spokesperson confirmed to Business Insider that departures were suspended.

"We are currently responding to a drone sighting at Heathrow and are working closely with the Met Police to prevent any threat to operational safety," the spokesperson said in a statement to Business Insider. "As a precautionary measure, we have stopped departures while we investigate. We apologize to passengers for any inconvenience this may cause."

Read more: These are the 20 busiest airports in the world.

Heathrow is one of the largest airports in the world, with around 100,000 departures per day. It's also the busiest airport in Europe and the seventh busiest in the world with more than 78 million passengers annually. 

Read More: Video shows the damage a drone can do to a plane, as Gatwick Airport shuts down over rogue drones on the runway

The shut down follows a 32-hour hold on flights at London's Gatwick Airport last month. More than 120,000 people had had their journeys disrupted as a result of the Gatwick shut down. However, following the closure, British police said the drone sightings may not have actually been genuine.

This is a developing story.