BRUSSELS (AFP) - The EU warned US tech giants Thursday (April 26) to crack down on the spread of "fake news" by the end of the year or face regulation in the wake of a scandal involving the illegal harvesting of Facebook users' data.

Brussels called for the creation of a network of "independent fact-checkers" and a code of conduct amid growing concerns over election meddling involving the use of the Internet and personal data.

"We are giving social networks and online platforms a chance to resolve the problem once and for all," EU digital commissioner Mariya Gabriel told a news conference.

As a first step, the Bulgarian commissioner called on tech firms to draw up a code of conduct by July, and proposed the creation of a secure online platform to tackle "disinformation".

"We will closely monitor the progress made and may propose further actions by December, including measures of regulatory nature, should the results prove unsatisfactory," she warned.

A European Commission statement explicitly referenced the scandal over the massive leak of Facebook user data to British consultancy Cambridge Analytica for use in the election campaign of US President Donald Trump.

"The recent Facebook/Cambridge Analytica revelations demonstrated exactly how personal data can be exploited in electoral contexts, and are a timely reminder that more is needed to secure resilient democratic processes," the statement said.

Brussels has repeatedly raised concerns over meddling in elections including alleged Russian interference in the 2016 US presidential ballot and the Brexit vote in Britain the same year.

French President Emmanuel Macron said in an address to the US Congress on Wednesday that "to protect our democracies, we have to fight against the ever-growing virus of fake news".

The EU plans come after a group of 40 media experts including AFP produced a report on the issue earlier this year.

Brussels meanwhile also pressed Silicon Valley firms like Google to be more transparent about how their search results work amid concerns that they are squeezing out small businesses.

"We must make sure they are not abusing their power," Gabriel said.

Google was hit last June with a 2.4-billion-euro (more than US$2.7 billion) EU fine for illegally favouring its shopping service in search results, after which it proposed fixes including running the shopping arm as a standalone business.

The EU has taken an increasingly tough stance on US tech firms, with plans announced in March for a digital tax on Silicon Valley giants riling Washington.