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In only a few years, the surveillance start-up Flock has installed more than 100,000 license plate reader cameras across the United States.

But a grassroots movement upset over privacy concerns is fighting back — even going so far as systematically vandalising the equipment.

The first time he decided to trash one of the cameras, a self-styled vigilante wearing all black and known as Nomark says he was “super nervous”.

Now, after disabling about 30 of the devices near his home in the Minneapolis area, he told AFP: “I’m not really as scared anymore.”