Police have vowed to arrest environmental protesters if they go ahead with plans to disrupt flights at Heathrow airport by sending drones into the air.

Heathrow Pause, an offshoot of Extinction Rebellion, says the devices will be flown at head height and away from flightpaths on Friday to avoid any safety risk.

But the Metropolitan Police said the action would be “criminal” and anyone taking part would be arrested.

Deputy assistant commissioner Laurence Taylor said police had been preparing for the demonstration for weeks to minimise any potential disruption to flights at Britain’s busiest airport.

“Far from this being a lawful protest, this is the deliberate and criminal targeting of an essential part of the UK’s national infrastructure that thousands of people rely on every day and it will not be tolerated,” he added.

Extinction Rebellion: Climate change protests cause chaos in London Show all 46 1 /46 Extinction Rebellion: Climate change protests cause chaos in London Extinction Rebellion: Climate change protests cause chaos in London Canary Wharf A protester gives a thumbs up as he stalls a DLR train at Canary Wharf station in London Reuters Extinction Rebellion: Climate change protests cause chaos in London City of London Protesters hold up traffic on Upper Thames Street in the City of London Getty Extinction Rebellion: Climate change protests cause chaos in London Canary Wharf Protesters hold a banner as they hold up a DLR train at Canary Wharf station in London Reuters Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Officers remove plants that were placed in the occupation of Waterloo Bridge PA Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Police officers arrive at Oxford Circus as they prepare to remove protesters during the fifth day of a coordinated protest by the Extinction Rebellion group, April 19 Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge An activist waters the plants at the occupation on Waterloo Bridge PA Extinction Rebellion: Climate change protests cause chaos in London Heathrow airport Undeterred by over 400 arrests, climate change activists continued their demonstration into a fifth day in London with a small protest at the country's main Heathrow Airport, along with the ongoing protest camps at other iconic locations around the British capital Reuters Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Protesters with the words 'glued on' written on their hands hold hands as police officers arrive at Oxford Circus Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Officers circle the lorry that serves as the central stage to the Waterloo Bridge occupation, repeating their tactic from a earlier at the Oxford Circus occupation Reuters Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Oxford Circus reopens after being closed for days due to occupation AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Officers prepare to move in on the occupation of Waterloo Bridge PA Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Activists relax on a sofa at the occupation on Waterloo Bridge AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus British actress Emma Thompson talks to members of the media from atop the pink boat after police officers surrounded the boat being used as a stage as climate change activists occupy the road junction at Oxford Circus in central London during the fifth day of environmental protesst by the Extinction Rebellion group AFP Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge An Extinction Rebellion demonstrator is carried away by police on Waterloo Bridge PA Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Activists on Waterloo Bridge have made a garden for their occupation site, April 20 Reuters Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Demonstrators began blocking off a bridge and major central road junctions on April 15 at the start of a civil disobedience campaign calling for governments to declare an ecological emergency over climate change, to reduce greenhouse gas emissions to zero by 2025, halt biodiversity loss and be led by new "citizens' assemblies on climate and ecological justice" Reuters Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Emma Thompson joins the Extinction Rebellion protest at Oxford Circus. Thompson spoke from the pink boat at the centre of the occupation AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Heathrow airport Extinction Rebellion protesters sit outside Heathrow Airport on April 19 Reuters Extinction Rebellion: Climate change protests cause chaos in London Heathrow airport Climate protestors hold a demo outside Heathrow Airport Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Police officers detain a climate change activist at Waterloo Bridge Reuters Extinction Rebellion: Climate change protests cause chaos in London Marble Arch Protesters prepare for another day at Marble Arch as the Extinction Rebellion protests enter their fifth day Getty Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus British actress Emma Thompson gives an address from the stage atop the pink boat AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Actress Emma Thompson takes a photo with a Extinction Rebellion demonstrator PA Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Climate change activists blockade Oxford Circus on the third day of an environmental protest by the Extinction Rebellion group AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Climate change activists stand atop a bus shelter as they take part in a blockade of Waterloo Bridge AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Canary Wharf Police is seen as climate change activists demonstrate during the Extinction Rebellion protest, at Canary Wharf DLR station in London Reuters Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Police speak to climate change activists blockading Waterloo bridge AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge epa07511673 A demonstrator gestures the hand heart as protesters from the Extinction Rebellion campaign group block Waterloo Bridge in central London, Britain, 17 April 2019. The Extinction Rebellion are holding a number of protests across London to draw attention to climate change. EPA/NEIL HALL NEIL HALL EPA Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Climate change activists, one (right) with her hand glued to the underside of a truck parked across Waterloo Bridge AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Environmental campaigners protest in the centre of Oxford Circus Getty Extinction Rebellion: Climate change protests cause chaos in London Jeremy Corbyn's Home Climate change activists from Extinction Rebellion protest sit after glueing themselves to the front fence of Britain's opposition Labour Party leader Jeremy Corbyn's house Reuters Extinction Rebellion: Climate change protests cause chaos in London Marble Arch Dozens of tents have been pitched at Marble Arch in a large scale occupation Reuters Extinction Rebellion: Climate change protests cause chaos in London Canary Wharf station Police remove climate activists who glued themselves on top of a train at Canary Wharf station EPA Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Police forces carry a protester AP Extinction Rebellion: Climate change protests cause chaos in London Canary Wharf station A climate change protestor who glued his hand to a window halts a DLR train AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Extinction Rebellion demonstrators on Waterloo Bridge, London, after police issued a Section 14 Public Order Act 1986 warning. PRESS ASSOCIATION Photo. Picture date: Wednesday April 17, 2019. See PA story ENVIRONMENT Climate. Photo credit should read: Jonathan Brady/PA Wire Jonathan Brady PA Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge epa07512336 Extinction Rebellion climate change demonstrators protest on Waterloo Bridge during climate change protests in London, Britain, 17 April 2019. The Extinction Rebellion are holding a number of protests across London to draw attention to climate change. EPA/ANDY RAIN ANDY RAIN EPA Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge epa07512368 Extinction Rebellion climate change demonstrators protest on Waterloo Bridge during climate change protests in London, Britain, 17 April 2019. Waterloo Bridge remains closed as protests continue. EPA/ANDY RAIN ANDY RAIN EPA Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Extinction Rebellion demonstrators in Oxford Circus, London, as more than 200 people have been arrested as police deal with ongoing climate change protests. PRESS ASSOCIATION Photo. Picture date: Wednesday April 17, 2019. See PA story ENVIRONMENT Climate. Photo credit should read: Kirsty O'Connor/PA Wire Kirsty O'Connor PA Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus LONDON, ENGLAND - APRIL 17: An Environmental campaigner is carried by police officers at Oxford Circus during the third day of a coordinated protest by the Extinction Rebellion group on April 17, 2019 in London, England. More than 100 arrests have been made, with demonstrations blocking a number of locations across the capital. (Photo by Leon Neal/Getty Images) Leon Neal Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Pedestrians and a cyclist pass graffiti drawn by protestors who blocked Waterloo Bridge AP Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Climate change protestors practice yoga on Waterloo Bridge AFP/Getty Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge A climate change activist gestures while being detained by police officers Reuters Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Protestors sit on the road AP Extinction Rebellion: Climate change protests cause chaos in London Waterloo Bridge Extinction Rebellion demonstrators on Waterloo Bridge, London, as more than 200 people have been arrested as police deal with ongoing climate change protests. PRESS ASSOCIATION Photo. Picture date: Wednesday April 17, 2019. See PA story ENVIRONMENT Climate. Photo credit should read: Yui Mok/PA Wire Yui Mok PA Extinction Rebellion: Climate change protests cause chaos in London Oxford Circus Police forces carry a protestor to arrest him at Oxford Circus in London, Wednesday, April 17, 2019. The group Extinction Rebellion is calling for a week of civil disobedience against what it says is the failure to tackle the causes of climate change. (AP Photo/Frank Augstein) Frank Augstein AP

“We would urge anyone planning to take part in this activity to reconsider. Airspace around all airports is restricted for public safety and security, and we take the flying of a drone within airspace used by passenger planes very seriously. Anyone caught flying a drone without permission must expect to be arrested and prosecuted.”

Mr Taylor cited the chaos caused by drone sightings that shut down Gatwick airport before Christmas as an example of the disruption such a protest could cause.

“Drone use in restricted airspace has the capability to not only cause a significant safety risk, but also cause great disruption to the public at the airport being targeted and connecting airports internationally,” he added.

“The police’s job is to detect and stop criminal activity in a proportionate way, and there is a robust policing plan in place to ensure that we are in a position to deal with any illegal activity as quickly and efficiently as possible.”

He urged air passengers to travel as normal on Friday, adding: “I would urge people to come on Friday because we’re going to do everything we can to prevent any disruption and I am confident we will be successful in that.

Heathrow Pause said its activists were “prepared to pay a very high price” to protest against the planned third runway at the airport, and are also calling for the government to “tell the truth” about global warming and act on parliament’s declaration of a climate emergency.

Demonstrators including Extinction Rebellion co-founder Roger Hallam met officers at a London station on Tuesday, and said they would cooperate with police “as far as possible”.

Heathrow Pause said the drones would be launched at 3am on Friday and then “at regular intervals throughout the day”, with advance notice given to relevant authorities.

No airline has cancelled flights as a result of Friday’s protest (PA)

In a statement, the group said its actions were a “humanitarian act intended to save millions of innocent lives that will be lost if carbon emissions are not drastically reduced”.

Valerie Milner-Brown, a 64-year-old writer who is to pilot one of the drones, said: “I don’t want to get arrested, but it feels like it’s the last resort for our government to take notice.

“I’m a grandmother and I care deeply about my children’s and grandchildren’s futures – and I would never do anything to put a life at risk.”

Mr Hallam said the Heathrow expansion would be the “biggest carbon-intensive infrastructure project in Europe”.

It comes after waves of Extinction Rebellion demonstrations across the UK and around the world, seeing more than 1,000 protesters arrested for blocking roads and bridges in London in April.

A spokesperson for Heathrow airport said it agreed with the need to act on climate change but disrupting passengers was “counterproductive and irresponsible”.

“Flying a drone within 5km of Heathrow is illegal and any persons found doing so will be subject to the full force of the law,” he added.