Social media and other websites will have just one hour to delete offending content under a new law passed by France’s parliament.
The one-hour deadline applies to content that French authorities consider to be related to terrorism or child sexual abuse.
Failing to act could result in fines of up to 4% of global revenue – billions of euros for the largest online firms.
But critics say the new law could restrict freedom of expression.
The new rules apply to all websites, whether large or small. But there are concerns that only internet giants such as Facebook and Google actually have the resources to remove content as quickly as required.
Digital rights group La Quadrature du Net said the requirement to take down content that the police considered “terrorism” in just one hour was impractical.
“Except the big companies, nobody can afford to have a 24/7 watch to remove the content when requested,” a spokesman for the group said. “Hence, they will have to rely on censorship before receiving a request from the police.”
That might be in the form of using an automatic system provided by the largest companies, giving them “more power on what can exist on the web or not”.
But there are also fears that such tech could be used against groups such as protesters.