The company is also changing its advertising policies, including allowing only authorized groups to buy political ads. A new verification process will eventually require advertisers to be based in the country where the election is taking place.

In addition, Facebook is planning to introduce a searchable database to show how much an advertiser is spending, as well as the demographic details of the audience that a group is trying to reach.

Padraic Ryan, projects coordinator for the social media verification service Storyful, said that Facebook’s move was a welcome one. But he added that countries like Ireland needed to formulate their own rules, rather than rely on private companies.

“This is about regulation and transparency,” Mr. Ryan said. “It’s not just about Facebook.”

He added: “We’ve seen preroll ads on YouTube, display ads on any number of sites, suggested results on Google linking to pro- or anti- pages, and it’s not at all clear who is behind these. It seems manifest now that there should have been rules regulated before the fact.”

Google and its video-sharing service, YouTube, did not immediately respond to a request for comment.

Europe in particular has become a testing ground for some of Facebook’s changes to protect against political interference. Before the German election in September, for example, the company deleted thousands of fake accounts and worked with election officials to stop the spread of misinformation more quickly.

Researchers are now focused on the referendum in Ireland, and the platform’s role in the campaign.

Last week, Gavin Sheridan, a former employee for Storyful, was able to trace one web page, ostensibly an information source for undecided voters but with no verifiable identification or contact details, to conservative Roman Catholic groups in the United States. The page seemed designed, Mr. Sheridan said, to draw in undecided voters, who would then be targeted with personalized ads for the campaign that seeks to maintain Ireland’s conservative abortion laws.