Facebook is cracking down on advertisements that promise to cure or prevent the coronavirus as some take advantage of fear about the epidemic spreading around the world.

The social media giant said it is working to stop ads that “refer to the coronavirus and create a sense of urgency.” The measure covers ads that guarantee the virus will be prevented or cured as well as those suggesting a limited supply, according to Facebook.

“For example, ads with claims like face masks are 100 percent guaranteed to prevent the spread of the virus will not be allowed,” a Facebook spokesperson said in a statement Wednesday.

The move followed reports that Facebook has become a marketplace of sorts for medical face masks, which have been in short supply amid fears about the coronavirus. Scammers on the site duped about 100 people in Hong Kong into paying as much as roughly $51 for boxes of masks that were never delivered, the South China Morning Post reported last week.

Facebook also pledged last month to take down posts spreading false claims and conspiracy theories about the coronavirus, which has killed more than 2,700 people worldwide and spread from China to countries including the US, Italy and South Korea. Those efforts also apply to advertisements, according to the company.

The step marked an unusually aggressive effort to combat misinformation by Facebook, which has drawn fire for allowing political campaigns to run advertisements containing false claims.

This story originally appeared in the New York Post.