Members of the "yellow vests" protest movement have vandalised almost 60% of France's entire speed camera network, the interior minister has said, reports the BBC.
Christophe Castaner said the wilful damage was a threat to road safety and put lives in danger.
The protest movement began over fuel tax increases, and saw motorists block roads and motorway toll booths.
Some protesters feel speed cameras are solely a revenue-generating measure which takes money from the poor.
The BBC's Hugh Schofield, in Paris, said evidence of the vandalism is visible to anyone driving around France, with radar cameras covered in paint or black tape to stop them working.
But the extent of the damage - now believed to affect more than half of all 3,200 speed cameras in the country's network - was unknown until Mr Castaner's statement on Thursday.