Police have arrested 19 people believed to be involved in a climate change protest at Heathrow Airport.
Heathrow Pause activists threatened to fly drones in the exclusion zone, but no flight disruption has been reported.
The arrested people have all been held on suspicion of conspiracy to commit a public nuisance.
Heathrow Pause said one of the arrested - Roger Hallam, an Extinction Rebellion co-founder - was still planning to fly a drone on Saturday.
The group said Mr Hallam was released from custody at about 22:00 BST on Friday and that he would be flying the drone "near Heathrow" with the location "to be announced nearer the time".
The Metropolitan Police said that, out of those arrested, four remained in custody on Friday night. The others have been bailed.
Police say those arrested range in age from 19 to 69.
A 53-year-old man who was arrested on Friday was re-arrested on Saturday. He remains in police custody.
Heathrow Pause had previously said it intended to fly drones within the 5km exclusion zone around the airport on Friday morning, but the group claimed the airport was using "signal jamming to frustrate" their efforts.
Both the airport and police refused to comment on "security matters".
The Met Police said a dispersal order at the airport would be effective until early on Sunday morning.
Deputy Assistant Commissioner Laurence Taylor said: "We are really clear that [flying drones] is unlawful, it is a criminal offence, and anybody who turns up expecting to fly drones in that exclusion zone will be arrested."
The force made seven pre-emptive arrests on Thursday, including that of Extinction Rebellion co-founder Roger Hallam.
Heathrow Airport said it was committed to addressing climate change, but this was best tackled through "constructive engagement and working together to address the issue".