MPs are launching a parliamentary inquiry into the “growing phenomenon of fake news”.
The Culture, Media and Sport Committee said it would investigate concerns about the public being swayed by propaganda and untruths.
The inquiry will examine the sources of fake news, how it is spread and its impact on democracy.
Claims that voters in the US election were influenced by fake news spurred the inquiry, the committee said.
Damian Collins, the committee chairman, said the rise of propaganda and fabrications is “a threat to democracy and undermines confidence in the media in general”.
“Just as major tech companies have accepted they have a social responsibility to combat piracy online and the illegal sharing of content, they also need to help address the spreading of fake news on social media platforms,” he said.
“Consumers should also be given new tools to help them assess the origin and likely veracity of news stories they read online.
“The committee will be investigating these issues as well as looking into the sources of fake news, what motivates people to spread it and how it has been used around elections and other important political debates.”
The MPs want to investigate whether the way advertising is bought, sold and placed online has encouraged the growth of fake news.
They also want to address the responsibility of search engines and social media to stop spreading it.
New research suggests that online hoaxes and propaganda may have only had limited impact in the US presidential election, however.
According to a study by two US economists, fake news which favoured Donald Trump was shared 30 million times in the three months before the election, four times more than false stories favouring Hillary Clinton.
But the authors said that only half of people who saw a false story believed it, and even the most widely circulated hoaxes were seen by only a fraction of voters.