U.K. police have arrested a number of environmental activists affiliated with a group which announced last month that it would use drones to try to ground flights at the country’s busiest airport.

The group, which calls itself Heathrow Pause, is protesting against the government decision to green-light a third runway at the airport.

In a press release published today about an operation at Heathrow Airport, London’s Met Police said it has arrested nine people since yesterday in relation to the planned drone protest, which had been due to commence early this morning.

Heathrow Pause suggested it had up to 200 people willing to volunteer to fly toy drones a few feet off the ground within a 5km drone “no fly” zone around the airport — an act that would technically be in breach of U.K. laws on drone flights, although the group said it would only use small drones, flown at head height and not within flight paths. It also clearly communicated its intentions to the police and airport well in advance of the protest.

“Three women and six men aged between their 20s and the 60s have been arrested on suspicion of conspiracy to commit a public nuisance,” the Met Police said today.

“Four of the men and the three women were arrested yesterday, Thursday, 12 September, in Bethnal Green, Haringey and Wandsworth, in response to proposed plans for illegal drone use near Heathrow Airport.

“They were taken into custody at a London police station.”

The statement says a further two men were arrested this morning within the perimeter of Heathrow Airport on suspicion of conspiracy to commit a public nuisance — though it’s not clear whether they are affiliated with Heathrow Pause.

Videos of confirmed members of the group being arrested by police prior to the planned Heathrow Pause action have been circulating on social media.

Roger Hallem , our brave drone pilot being arrested preemptively . We will not give up and we urge all right minded people to rise up with us . Don't sleep walk into oblivion . Protect your children as if their lives depended on it . It does @ExtinctionR @GretaThunberg pic.twitter.com/10gpVtVVEF — Heathrow Pause (@HeathrowPause) September 12, 2019

In an update on its Twitter feed this morning Heathrow Pause says there have been 10 arrests so far.

It also claims to have made one successful flight, and says two earlier drone flight attempts were thwarted by signal jamming technology.

More flights are planned today, it adds.

UPDATE: 3 attempted flights, at least one successful. 10 arrests so far. More flights planned today. James, having completed his flight, is about to hand himself into police. Currently in Heathrow Terminal 2 Departures for interviews/photos. — Heathrow Pause (@HeathrowPause) September 13, 2019

Thank you James Brown for your courage. @HeathrowAirport when will you adhere by your own rules and close the airport? https://t.co/fJFlLx2dGb — Heathrow Pause (@HeathrowPause) September 13, 2019

A spokeswoman for Heathrow told us there has been no disruption to flights so far today.

In a statement the airport said: “Heathrow’s runways and taxiways remain open and fully operational despite attempts to disrupt the airport through the illegal use of drones in protest nearby. We will continue to work with the authorities to carry out dynamic risk assessment programmes and keep our passengers flying safely on their journeys today.”

“We agree with the need for climate change action but illegal protest activity designed with the intention of disrupting thousands of people, is not the answer. The answer to climate change is in constructive engagement and working together to address the issue, something that Heathrow remains strongly committed to do,” it added.

We’ve asked the airport to confirm whether signal jamming counter-drone technology is being used to try to prevent the protest.

The Met Police said a dispersal order under Section 34 of the Anti-social Behaviour, Crime and Policing Act 2014 has been implemented in the area surrounding Heathrow Airport today.

“It will be in place for approximately 48 hours, commencing at 04:30hrs on Friday, 13 September,” it writes. “The order has been implemented to prevent criminal activity which poses a significant safety and security risk to the airport.”