SAN FRANCISCO - Facebook on Monday said that pages that make a habit of linking to bogus news stories would no longer be able to advertise at the world's leading online social network.

The move is the latest shot fired by Facebook in its war against "fake news" used to deceive instead of enlighten.

"If Pages repeatedly share stories marked as false, these repeat offenders will no longer be allowed to advertise on Facebook," product managers Tessa Lyons and Satwik Shukla said in a blog post.

"This update will help to reduce the distribution of false news which will keep Pages that spread false news from making money."

The social network already didn't allow ads that link stories determined to be false by third-party fact-checkers.

"False news is harmful to our community," Lyons and Shukla said.

"It makes the world less informed and erodes trust."

Fake news became a serious issue in last year's US election campaign, when clearly fraudulent stories circulated on social media, potentially swaying some voters.

Concerns have been raised since then about hoaxes and misinformation affecting elections in Europe this year, with investigations showing how "click farms" generate revenue from online advertising using made-up news stories.

"We've found instances of Pages using Facebook ads to build their audiences in order to distribute false news more broadly," Lyons and Shukla said.

Facebook and Google have been working to curtail, or at least flag, stories crafted to deceive instead of enlighten.

Google earlier this year added a fact-checking tag to search results globally, its latest initiative to help curb the spread of misinformation and "fake news."

The new tags, to be used in all languages for users worldwide, use third-party fact-checkers to indicate whether news items are true, false or somewhere in-between.

The feature debuted about the same time Facebook added a new tool in news feeds to help users determine whether shared stories are real or bogus.

© Agence France-Presse