Fake news

But now the two web giants are under pressure over another kind of fakery - fake advertising.

On this week's Tech Tent we hear about the advertising industry's mounting anger over a problem that is damaging its credibility with its clients. When advertising began to move online, there was the promise of much better targeting and much more accurate measurement of how well a marketing message performed.

Instead all sorts of issues, from bots that generate phony views of ads to the placing of advertisements next to unsuitable content, have shaken confidence in the industry.

Germany's justice minister has drafted a law that seeks to impose the fines as part of efforts to police toxic chat.

Heiko Maas said the voluntary efforts of social networks to tackle the problem had not gone far enough.

The proposal requires sites to run 24-hour helplines and to delete flagged content within seven days.

'Utterly impossible'

Social media firms such as Twitter and Facebook were getting better at handling illegal content, said Mr Maas, but both had a long way to go.

Fake news, false stories that masquerade as real news are not new.

In the spring of 1917 some of Britain's most influential newspapers published a gruesome story that has been called "the master hoax" - and I think we finally have proof about where it came from.

Britain was at the time trying to bring China into the war on the Allied side.

In February a story appeared in the English-language North China Daily News that claimed the Kaiser's forces were "extracting glycerine out of dead soldiers".

In an impassioned plea, Cook, boss of the world's largest company, says that the epidemic of false reports "is a big problem in a lot of the world" and necessitates a crackdown by the authorities and technology firms.

He calls for a campaign similar to those that changed attitudes on the environment to educate the public on the threat posed by fabricated online stories. Made-up news reports trying to promote a particular agenda gained huge traction on social media in the US during the election.

Google and Facebook are partnering with journalists to help prevent fake news stories from spreading during France's presidential election.

Google News Lab and the non-profit First Draft News have launched a verification project called "CrossCheck" that will help French newsrooms identify and quickly debunk hoaxes, rumors and other false claims.

At least 17 major news organizations are taking part in the project, including Le Monde, Agence France-Presse (AFP), Liberation, BuzzFeed and France Medias Monde, which manages Radio France Internationale and TV station France 24.

The world's largest social network said it would enable German users to flag potentially false stories.

The stories will then be passed to third-party fact-checkers and if found to be unreliable, will be marked in users' news feeds as "disputed".

It is the first major rollout of the fake news features announced by Facebook in December.

The 2016 Presidential Election exposed the un-apologetic hypocrisy in the American media about journalism ethics. “Yellow journalism” made a comeback unprecedented since its hay days in the 1890s. New York newspaper publishers William Randolph Hearst (New York Journal) and Joseph Pulitzer (New York World), sensationalized their headlines, and with fraudulent stories to increase their circulation profits. 

New reporting features are being rolled out, along with other changes designed to combat the spread of misinformation.

Facebook was widely criticised last month after some users complained that fake news had influenced the US presidential election.

The new features include the ability to flag fake stories, as well as possible future changes to Facebook's algorithm.

In a post on his Facebook profile Mr Zuckerberg said he hoped to announce measures to tackle fake stories "soon".

He said this work "often takes longer than we'd like in order to confirm changes we make won't introduce unintended side effects or bias".

And he said that more than 99% of content on Facebook "is authentic".

"Only a very small amount is fake news and hoaxes. The hoaxes that do exist are not limited to one partisan view, or even to politics," he added.

While the internet has enabled the sharing of knowledge in ways that previous generations could only have dreamed of, it has also provided ample proof of Winston Churchill's line that "A lie gets halfway around the world before the truth has a chance to get its pants on".