A South African company has begun supplying a drone to an international mining company that is designed to shower pepper spray on unruly crowds.
Desert Wolf claims it wants to help in "preventing another Marikana"- a reference to a protest in August 2012 at which 34 striking mineworkers were shot and killed during clashes with police.
Branded "The Skunk", the riot control drone was condemned by labour activists as "absolutely outrageous" and compared with deadly US military drones in Pakistan.
Desert Wolf, based in Pretoria, unveiled the 500,000 rand (HK$362,000) machine at a recent trade show as "designed to control unruly crowds without endangering the lives of the protesters or the security staff".
The Skunk has eight electric motors with 40cm propellers that can lift 45kg and carry 4,000 pepper-spray balls or other "non-lethal" ammunition.
The device is equipped with four barrels firing up to 20 balls per second each, which could equate to 80 pepper-spray balls per second "stopping any crowd in its tracks".
It is also fitted with strobe lights, "blinding lasers" and on-board speakers to give verbal warnings to crowds. It has a thermal camera and high-definition video camera with on-board recording.
There was an immediate backlash against the technology. James Nichol, a British lawyer representing the families of dead strikers at Marikana, said: "It's absolutely outrageous. Using pepper spray like ammunition to scatter the crowd. People are entitled to be on strike. Who would make the decision? It's absurd."
He added: "What we know about drones is in Pakistan they have killed funeral parties and they have killed wedding parties. Innocent people would be caught up in this. It seems to be the thin end of the wedge."
Tim Noonan, a spokesman for the International Trade Union Confederation, told the BBC: "This is a deeply disturbing and repugnant development and we are convinced that any reasonable government will move quickly to stop the deployment of advanced battlefield technology on workers or indeed the public involved in legitimate protests and demonstrations."