The "growing phenomenon of fake news" is to be the subject of a parliamentary inquiry.
Earlier this month, the Telegraph revealed that an influential cross-party group of MPs were planning to grill executives at Facebook, Google and Twitter about the issue.
Now, the Culture, Media and Sport Committee is officially launching the probe into the "widespread dissemination, through social media and the internet, and acceptance as fact of stories of uncertain provenance or accuracy".
Explaining the reason for the inquiry, the committee noted concerns over people being fed propaganda and untruths from non-traditional news sources.
The fear has been strengthened by suggestions that voters in the 2016 US presidential election were subjected to "possibly unprecedented" amounts of fake news, the committee said.
Damian Collins, chairman of the committee, said the trend was "a threat to democracy and undermines confidence in the media in general".