FILE - A photo shows a large screen at Heathrow Airport Terminal 2 in London, Britain, April 23, 2014.
FILE - A photo shows a large screen at Heathrow Airport Terminal 2 in London, Britain, April 23, 2014.

A group of British environmental activists have postponed their plan to ground flights at London's Heathrow Airport.

Extinction Rebellion had planned to use drones to paralyze Europe’s busiest airport intermittently in June and July to draw attention to the environmental harm that would be caused by the planned third runway.

The first of the protests was to take place Tuesday.

“Extinction Rebellion will not be carrying out any actions at Heathrow Airport in June or July this year,” the group said in a statement. “The Heathrow Airport authorities will therefore not have to pause any summer flights.”

On Friday, British law enforcement authorities warned the activists that flying drones would result in life in prison for the participants.

Heathrow Airport called the planned action "reckless", saying it "could endanger the lives of the traveling public and our colleagues".

But the group rejected claims that its actions could cause harm.  The group said it is not abandoning its plans for drone protests. On Sunday, it detailed its plans saying the lightweight drones would only be flown at head height within the 5 kilometer exclusion zone around Heathrow, forcing the airport to ground flights.   It did not disclose the dates for its protests.

"There is nothing violent about flying drones when there are no flights in the air as it is perfectly safe," the group said in a statement. "We are there first. The responsibility is with the airport authority to not initiate flights.”

Extinction Rebellion said its aim was to achieve "economic disruption" not to hurt people.

In December, thousands of flights were grounded at Gatwick Airport outside London after drones were spotted flying around it.

Extinction Rebellion says it was not responsible for that action.