Facebook has unveiled a string of measures it is introducing to ensure users are not presented with fake news on the site.

The move follows an onslaught of criticism directed at the social media giant centred on concerns it was not taking effective action to stop people's feeds being swamped with false reports.

Users will soon be able to flag up when they believe a story is a hoax, which can result in them being sent to "third-party fact checking organisations" for review, Facebook said.

If concerns about the piece's validity are echoed by the groups, which the social media site has drafted in for assistance, an alert will appear underneath warning that it has been disputed.

False stories could also be bumped further down newsfeeds and cannot be made into an advert or promoted, Facebook said.

But users will still have the ability to share such stories to their online friends.

Vice president of Facebook's News Feed Adam Mosseri said: " We believe in giving people a voice and that we cannot become arbiters of truth ourselves, so we're approaching this problem carefully.

"We've focused our efforts on the worst of the worst, on the clear hoaxes spread by spammers for their own gain, and on engaging both our community and third party organisations."

A row erupted over the role Facebook had in tackling the growing problem in the aftermath of Donald Trump's shock US election win, with critics pointing to scores of fictitious but widely shared articles smearing his opponent, Hillary Clinton.

Founder Mark Zuckerberg initially rubbished the claims, saying it was a "pretty crazy idea" that fake news could have influenced the election.

Mr Mosseri said the rise of bogus stories could be blamed in part on financial motivations - as spammers can profit from advert revenues by luring social media users in with scandalous, but inaccurate, headlines.

"It's important to us that the stories you see on Facebook are authentic and meaningful. We're excited about this progress, but we know there's more to be done. We're going to keep working on this problem for as long as it takes to get it right," he added.