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.

“If the site does not censor the content, for example because the report is sent on a weekend or overnight, the police can require [the whole site] to be blocked everywhere in France by internet service providers,” it said.

It said the power to decide what should be removed should not lie with the police but with judges.
Incitement to hatred

France’s new law reflects one proposed at the European Union level, where law-makers last year suggested a one-hour deadline for the removal of content.

But that proposal proved controversial and is currently in limbo.

France pushed ahead with its own version of the law despite the concerns in Europe.

Under the new French law, content judged to be illegal - but not relating to terrorism or child sexual abuse - will have to be taken down within 24 hours of notification.

That includes posts inciting hatred, violence, racism, and sexual harassment.

Failure to remove content could attract a fine of up to €1.25m (£1.1m).

France’s regulator, the Superior Council of the Audiovisual (CSA), will have the power to impose heftier fines of up to 4% of global turnover for continuous and repeated violations.

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Laetitia Avia, the MP from President Macron’s LREM party who proposed the bill, said the law would protect victims, while reaffirming the country’s commitment to freedom of expression.

However, France’s Republicans party voted against the measure.

Member Constance Le Grip told the National Assembly that fighting online hatred could not come at the expense of freedom of expression.

Her colleague in the Senate Bruno Retailleau tweeted that the new law was “incompatible with respect for public freedoms”.

Facebook said it was working closely with French regulator CSA and others “on the implementation of this law”.

YouTube said it already tackled illegal content and welcomed any new partnership with governments.

Twitter’s head of public affairs in France, Audrey Herblin-Stoop, told Reuters that the company would continue to work with the government to fight illegal content and hate speech.

The country’s digital minister confirmed the request in an interview given to Bloomberg.

France’s system would let it glean more information about participating smartphone owners than Apple and its partner Google want to allow.

Privacy experts view it as a test case.

“Apple has no reason to agree to this demand and it would open the door to many other requests from other countries and entities,” Prof Olivier Blazy from the country’s University of Limoges, told BBC News.

“As a Frenchman, I think it would be useful to avoid being dependent on the Google-Apple solution but I think it’s strange that the government strategy relies on trying to convince Apple to do something that is against its interest, with no incentive to do so.”

Apple and Google announced on 10 April they were working together to provide a software building-block - known as an application programming interface (API) - that will let authorised Covid-19 contact-tracing apps work more efficiently.

Contact-tracing apps work by logging every time two or more users are close to each other for a substantial period of time.

If one device owner is subsequently diagnosed as being likely to have the virus, an alert can be sent to those they could have infected, who might be asked to self-isolate.

By using such an app in conjunction with other measures, it would in theory be possible to end wider lockdowns and still suppress the disease, so long as enough people take part.

Apple and Google’s method relies on using Bluetooth signals to detect matches.

But they have deliberately designed it so neither they nor the apps’ creators can see who has been given a warning.

The companies have said this is to guarantee “strong protections around user privacy”, which in turn should encourage adoption.

By contrast, Inria - the French institute developing its StopCovid app - has developed a system of its own, called Robert (robust and privacy-preserving proximity tracing protocol).

It published details about it on Sunday on the code-sharing site Github.

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And although the French government has promised adoption of the app will be voluntary and involve anonymised data, the document reveals there would be ways to “re-identify users or to infer their contact graphs” if desired.

“It’s a misnomer to call it a privacy-preserving protocol,” said University of Oxford computer scientist Prof Max van Kleek, who prefers the Apple-Google design.

"It does preserve privacy between users but not between the user and the government.

“And that leads to the risk that the government later repurposes the system to make sure that people obey a quarantine or other kinds of things the state might want to know.”

The problem for Inria - and other countries developing their own contact-tracing apps - is Apple currently will not allow Bluetooth-based track-and-tracing to be carried out in the background.

So to work, the apps would have to remain active and on screen, limiting what else owners could do with their handsets and taking an extra toll on battery life.

The developers of Singapore’s TraceTogether app attempted to get round this problem by offering a Power Save mode, which dims the display.
Image copyright Getty Images
Image caption Users have complained about TraceTogether’s need to run in the foreground, in App Store reviews

But users have still complained of being unable to make calls or use other apps at the same time and having accidentally bumped the app into the background when their handset was in their pocket.

And this has discouraged people from using it.

“We’re asking Apple to lift the technical hurdle to allow us to develop a sovereign European health solution that will be tied to our health system,” France’s Digital Minister, Cedric O, told Bloomberg.