Facebook said on Friday it would make advertising on its network more transparent, amid increased scrutiny of political spending on social media.

Advertisers will be required to include a disclosure in election-related ads, which will read: "Paid for by," Facebook said. Facebook's users will be able to view the ads any Facebook page is running, whether or not they are the intended target audience for the ad.

The social netwrk will begin testing the feature in Canada.

"When it comes to advertising on Facebook, people should be able to tell who the advertiser is and see the ads they're running, especially for political ads," Rob Goldman, vice president of ads at Facebook said in a blog post.

Facebook, Twitter and Google have in recent weeks said Russian operatives bought ads and used fake names on their services to spread divisive messages in the run-up to the 2016 U.S. presidential election.

On Tuesday, Twitter said it would add labels to election-related ads and say who is behind each of them.