If the Government does not cancel all Heathrow expansion, Extinction Rebellion will act to shut the airport down for up to 10 days from July 1.
Extinction Rebellion (XR) has threatened to shut down Heathrow Airport for 10 days using drones if the Government does not cancel a planned expansion.
The environmental group, which brought London to a standstill for two weeks in April, said it will first stage a one-day protest on June 18.
It said if plans to expand Heathrow are not immediately scrapped the 10-day demonstration will begin on July 1. Holidaymakers were being given advance notice to "change travel plans", the group added.
It is understood the plans to use drones are contained in a document shared between members of the group. Heathrow said the plan was "reckless" and could "endanger lives".
A statement on the XR website said: "Extinction Rebellion demands the Government begins to act on its declaration of a Climate and Environment Emergency by cancelling all Heathrow expansion.
"On June 18, we plan to carry out nonviolent direct action to ensure Heathrow Authorities close the airport for the day, to create a 'pause' in recognition of the genocidal impact of high carbon activities, such as flying, upon the natural world.
"If the Government does not cancel all Heathrow expansion, Extinction Rebellion will act to shut the airport down for up to 10 days from July 1. Extinction Rebellion is in the consultancy stage with its members on the proposed action."
Demonstrators also protested at Heathrow during the last round of protests in April but did not cause disruption to flights. A small group of mostly teenage activists briefly unfurled a banner near a tunnel which leads to Terminals 2 and 3 as several police officers watched on.
But protesters who plan to disrupt Heathrow Airport with drones could face life behind bars, the Government has now warned.
Aviation minister Baroness Vere said: "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."
The statement, published on Friday, added: "This is not about targeting the public, but holding the Government to their duty to take leadership on the climate and ecological emergency.
"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."
A Heathrow spokesman said: "This is 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 hard-working people prepare to spend a well-earned holiday with their family and friends."
Airport security chiefs facing a drone protest by climate activists at Heathrow could struggle against a sustained attack, an expert has said.
Professor David Dunn, who recently spoke at Parliament about drone threats, said detaining suspects before a demonstration is able to take place could be the most effective measure.
Heathrow has military grade anti-drone technology, but that would be seriously tested if the airport is bombarded with a stream of devices in "waves", he said.
Prof Dunn, a professor in international politics at the University of Birmingham, likened the threat by Extinction Rebellion to the 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.
"It depends how many there were, how coordinated they were and it would require a major police operation."
The academic, who addressed an All Party Parliamentary Group on Armed Drones event in May, said any policing operation would be "very expensive and require a lot of manpower".
Lewis Pennock is a reporter for the Press Association.