The social network is tweaking the algorithm that picks posts for feeds to do a better job of spotting "low quality" web pages.

Instead, the algorithm will seek out more informative posts.

It said the change was part of broader work it was doing to make Facebook less profitable for spammers.

Building trust

The change was aimed at sites that contained "little substantive content" and were set up only to profit from users' attention, it said.

Facebook said it had already worked on ways to stop spammers from advertising on the network and now it wanted to do more to take on "organic posts" that turned up in news feeds.

Users had told it they were "disappointed" when they clicked on links that seemed to point to a news site but instead put them on a page built largely around adverts, Facebook said.

And these included pages with intrusive pop-up or interstitial ads, or that used pornographic pictures for dating sites or shocking images for treatments that purported to tackle many different ailments.

Facebook said its analysis of hundreds of thousands of web pages helped it to identify those run by spammers.

And this "fingerprint" of a spam site was now being used to spot whether posts for feeds had similar characteristics.

Facebook said the updated algorithm would be rolled out across its many territories over the next few months.

"The change could help Facebook fight fake news, as fakers are often financially motivated and blanket their false information articles in ads," wrote Josh Constine on news site TechCrunch.

He added that the change was important as it would help build trust in the content users were being fed.