Facebook’s ongoing experimentation with the content of the News Feed is boosting posts that promote fake news, reports The New York Times. The social networking site is currently testing a feature that separates users’ posts from content from professional news sites. News stories are instead placed in a separate feed called Explore, which is being tested in Slovakia, Sri Lanka, Cambodia, Bolivia, Guatemala, and Serbia.

According to the NYT, one false story that spread on Facebook in Slovakia because of these changes was about a Muslim man who supposedly thanked someone for returning his lost wallet by warning them about a planned terrorist attack. The story was so widely shared that local police had to issue a statement rejecting it. However, because the police alert came from an official account, it did not appear in users’ News Feeds.

In addition to the proliferation of fake news, publishers in the countries where the system is being tested say that traffic to their news sites has also plummeted with these changes, according to the NYT. Facebook hasn’t indicated when these tests will end.

An editor in Bolivia of the news site Página Siete said half of its traffic came from social media, with the majority from Facebook. Since the News Feed changes, overall web traffic to the site has dropped 20 percent. An editor in Cambodia noted that users thought politics had been purged from the social networking site altogether and did not know news posts were now appearing in a separate feed.

Facebook said in a statement to the NYT that the company takes its role as a global platform for information seriously. “We have a responsibility to the people who read, watch and share news on Facebook, and every test is done with that responsibility in mind,” Adam Mosseri, head of Facebook’s News Feed, told the publication.

Last week, Facebook said it plans to transform the News Feed to promote “meaningful posts” that highlight content from friends, while demoting posts from brands and publishers. (These changes are not the same as those introduced in Explore, but both do favor posts from friends rather than news and brand pages). We’ve reached out to Facebook for comment and will update this story if we hear back.