Extinction Rebellion protesters who plan to disrupt Heathrow Airport with drones could face life behind bars, the Government has warned.
The environmental group has announced it will cause 10 days of disruption in July unless plans to expand the airport are scrapped.
Activists have held internal discussions about using drones to ground flights under plans described by Heathrow as “reckless” and dangerous.
Several hours after the demonstration was announced on Friday, aviation minister Baroness Vere issued a stark warning that culprits will face “the full force of the law”.
The Metropolitan Police has also said it will develop “strong plans” to counter the group, which brought parts of London to a standstill during two weeks of demonstrations in April.
An initial one-day protest will go ahead on June 18 to “pause” flights before a longer protest of “up to 10 days” begins on July 1, Extinction Rebellion said.
“Extinction Rebellion demands the Government begins to act on its declaration of a climate and environment emergency by cancelling all Heathrow expansion,” a statement said.
The group described air travel as “genocidal”, adding: “The addition of the planned third runway would make Heathrow the single biggest carbon emitter in the UK; to expand the airport at this critical point in history would be madness.
“We understand the action will cause disruption to a great number of holidaymakers, however we believe that it is necessary given the prospect of far greater disruption caused by ecological and societal collapse, if we don’t act now.
“Holidaymakers are being given advance notice to change travel plans.”
Baroness Vere warned: “Flying drones near an airport is a serious criminal offence and using drones to deliberately put people’s safety at risk carries a maximum life sentence.
“No Government has done more to reduce carbon emissions, and Britain is at the forefront of global efforts to tackle climate change.
“Any illegal activity must be met with the full force of the law.”
The Department for Transport has said Heathrow expansion will only go ahead within the Government’s carbon reduction targets.
A Heathrow spokeswoman said the protest plans are a “reckless action that if carried out could endanger the lives of the travelling public and our colleagues”.
“We agree with the need to act on climate change, but that requires us to work together constructively – not commit serious criminal offences just as hardworking people prepare to spend a well-earned holiday with their family and friends,” she said.
In April thousands of XR supporters blocked key routes in London as the group demanded the Government announce a climate emergency.
A small group of mostly teenage activists unfurled a banner at Heathrow near a tunnel which leads to Terminals 2 and 3, but flights were not disrupted.
The Met is pushing for more than 1,100 people to be charged over the April protests and said others who disrupt Heathrow this summer will face justice.
“We will be developing strong plans in response to this and will take firm action against any protester seeking to cause disruption at this location by committing criminal offences such as obstruction of the highway,” a spokesman said.
“The airport is part of our national infrastructure and we will not allow illegal activities of some protesters to cause disruption and misery to thousands of travellers.
“We would urge anybody intending to join this event with a view to committing criminal activity, whether peaceful or not, to strongly reconsider.”
Professor David Dunn, a drones expert at the University of Birmingham, said arresting suspects ahead of the protests could be the most effective way to stop disruption.
He compared the threat to a drone incident at Gatwick Airport in December which affected roughly 140,000 passengers and 1,000 flights.
“Gatwick was probably two drones. But the underlying question is: what do you do if you have multiple drones, multiple directions, multiple wave incursions? They have not really got an answer for that,” he said.