The US Federal Trade Commission is reported to be investigating Facebook after allegations that 50 million users' private information was misused by a political consultancy firm.
Cambridge Analytica (CA), hired by the Trump campaign in the 2016 US election, has been accused of taking the personal data unknown to users.
CA head Alexander Nix has now been suspended by the company board.
The move came amid allegations the firm may have broken US electoral law.
CA, which is based in London, denies any wrongdoing.
Meanwhile, Facebook's stock has continued to slide , following a steep decline on Monday.
The British and European parliaments have called on Facebook boss Mark Zuckerberg to give evidence to them. , and the social network is due to brief congressional aides on Wednesday.
Mr Zuckerberg did not attend a Facebook staff briefing on the crisis at its Californian headquarters on Tuesday , which was led by deputy general counsel Paul Grewal instead, the Daily Beast news site reports.