LONDON — A cohort of international lawmakers is trying to turn up the pressure on Facebook, grilling one of its executives and making a show of founder Mark Zuckerberg's refusal to explain to them why his company failed to protect users' data privacy.

The rare "international grand committee" of lawmakers from nine countries gathered in London to get answers about Facebook's handling of personal data and made a point of leaving an empty seat with Zuckerberg's name tag.

Richard Allan, the company's vice president for policy solutions, said he volunteered to attend because Zuckerberg had already appeared before other committees this year, including in Washington and, briefly, Brussels.

Lawmakers from Canada, Ireland, Brazil, Argentina, Singapore, Belgium, France and Latvia joined their British counterparts at the parliamentary select committee hearing — the first such cross-border event in London since 1933. They want to scrutinize Facebook over its handling of data privacy, most notably involving consultancy Cambridge Analytica's improper use of information from more than 87 million Facebook accounts to manipulate elections.

British select committees are used to investigate major issues and have the powerful — from CEOs to government officials — explain their decisions in a public forum. They don't have the power to make laws but the government takes their recommendations into account when formulating new policies.