Environmental protesters planning to disrupt flights at Heathrow Airport could face "long jail sentences" for their actions, police have warned.
Heathrow Pause activists said they will operate small toy drones near the transport hub from 3am on Friday, September 13.
A spokesman for the group, which is separate to Extinction Rebellion, said they expect "somewhere between 50 to a couple of hundred people" to be involved in the action, with each person using a drone.
The Metropolitan Police have promised to do "everything in its power to prevent and stop any such criminal activity".
Deputy Assistant Commissioner Laurence Taylor said: "Heathrow Airport is part of our national infrastructure and we will not allow the illegal activity of protesters to cause misery to thousands of air travellers.
"The dangers of flying drones in airspace used by airliners carrying passengers are stark and the consequences potentially very severe.
"We would urge anybody intending to join this event with a view to committing criminal activity, whether considered peaceful or not, to think twice.
"Protesters should note that endangering the safety of an aircraft is a very serious offence that can result in a long jail sentence."
Heathrow Pause said their plans to fly the machines within the 5km zone surrounding the airport are "exploiting a loophole in Heathrow Airport's health and safety protocol".
They added: "Drones will not be flown in flight paths and there will be no risk of harm to anyone.
"We know that we will be arrested. We know that we face significant prison sentences for our actions. We have lives, we have families, we do not wish to go to prison.
"But we are steadfast in our resolve. We do this in defence of life. We do it because our consciences leave us no other choice but to act."
The activists said they will meet with police and airport authorities to discuss their plans on Friday.
A Heathrow spokesman said: "We agree with the need to act on climate change. This is a global issue that requires constructive engagement and action.
"Committing criminal offences and disrupting passengers is counter-productive.
"Flying of any form of drone near Heathrow is illegal and any persons found doing so will be subject to the full force of the law.
"We are working closely with the Met Police and will use our own drone detection capability to mitigate the operational impact of any illegal use of drones near the airport."
