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The appearance of fake news on websites and social media has inspired scientists to develop a "vaccine" to immunise people against the problem.

A University of Cambridge study devised psychological tools to target fact distortion.

Researchers suggest "pre-emptively exposing" readers to a small "dose" of the misinformation can help organisations cancel out bogus claims.

Stories on the US election and Syria are among those to have caused concern.

"Misinformation can be sticky, spreading and replicating like a virus," said the University of Cambridge study's lead author Dr Sander van der Linden.

"The idea is to provide a cognitive repertoire that helps build up resistance to misinformation, so the next time people come across it they are less susceptible."

The study, published in the journal Global Challenges, was conducted as a disguised experiment.

More than 2,000 US residents were presented with two claims about global warming.

The researchers say when presented consecutively, the influence well-established facts had on people were cancelled out by bogus claims made by campaigners.

But when information was combined with misinformation, in the form of a warning, the fake news had less resonance.

Fabricated stories alleging the Pope was backing Donald Trump and his Democratic rival Hillary Clinton sold weapons to the so-called Islamic State group were read and shared by millions of Facebook users during the US election campaign.

The world's largest social network later announced new features to help combat fabricated news stories, and there is pressure on Google and Twitter to do more to tackle the issue.

Meanwhile, German officials have reportedly proposed creating a special government unit to combat fake news in the run-up to this year's general election, while a senior Labour MP only last week warned that British politics risks being "infected by the contagion".

What is fake news?

The deliberate making up of news stories to fool or entertain is nothing new. But the arrival of social media has meant real and fictional stories are now presented in such a similar way that it can sometimes be difficult to tell the two apart.

There are hundreds of fake news websites out there, from those which deliberately imitate real life newspapers, to government propaganda sites, and even those which tread the line between satire and plain misinformation, sometimes employed to suit political ends.

The rise and rise of fake news