Facebook also said on Friday that it had suspended Canadian political consultancy AggregateIQ from its platform after reports that the data firm may have improperly had access to the personal data of Facebook users.

Facebook is under intense pressure after the data of millions of its users ended up in the hands of political consultancy Cambridge Analytica. Christopher Wylie, a whistleblower who once worked at Cambridge Analytica, has said that it worked with Canadian company AggregateIQ.

"In light of recent reports that AggregateIQ may be affiliated with SCL and may, as a result, have improperly received FB user data, we have added them to the list of entities we have suspended from our platform while we investigate," Facebook said in a statement.

"Our internal review continues, and we will cooperate fully with any investigations by regulatory authorities."

The Canadian federal agency charged with protecting privacy rights of individuals said on Thursday that the agency, along with its counterpart in British Columbia, would jointly investigate Facebook and AggregateIQ over the ongoing data scandal.

British Columbia's privacy commissioner was separately investigating AggregateIQ over whether the Victoria-based company had broken provincial personal privacy rules for its role in the Brexit campaign.

Facebook Canada said on Wednesday that more than 600,000 Canadians had their data "improperly shared" with Cambridge Analytica.

Facebook said on Wednesday that the personal information of up to 87 million users, mostly in the United States, may have been improperly shared with political consultancy Cambridge Analytica, up from a previous news media estimate of more than 50 million.

Limits Set on 'issue ads'

Facebook also backed for the first time on Friday proposed legislation requiring social media sites to disclose the identities of buyers of online political campaign ads and introduced a new verification process for people buying "issue" ads, which have been used to sow discord online.

The change in stance, announced in a Facebook post by Chief Executive Mark Zuckerberg, comes a few days before he is scheduled to answer questions in congressional hearings about how the company handles its users? data.

The steps are designed to deter the kind of election meddling and online information warfare that U.S. authorities have accused Russia of pursuing, Zuckerberg said. Moscow has denied the allegations.

"Election interference is a problem that's bigger than any one platform, and that's why we support the Honest Ads Act," Zuckerberg wrote in his post.

Zuckerberg said that he also wanted to shed more light on "issue ads," or ads that discuss a political subject such as gun laws or racism but do not directly relate to an election or a candidacy, and would require every such advertiser to confirm their identity and location.

"Any advertiser who doesn't pass will be prohibited from running political or issue ads," Zuckerberg wrote.

Facebook had previously stopped short of backing the legislation, saying it wanted to work with lawmakers further and announcing attempts at self-regulation.

Under the Honest Ads Act, digital platforms with at least 50 million monthly views would need to maintain a public file of all electioneering communications purchased by anyone spending more than $500.

The legislation would also require online platforms to make "all reasonable efforts" to ensure that foreign nationals and entities are not buying political ads to influence the U.S. electorate.

Facebook will also require verification of people who manage Facebook pages with large followings, Zuckerberg wrote.