LONDON • A British parliamentary committee yesterday asked Facebook chief Mark Zuckerberg to appear before it to explain in person claims that millions of users' data was harvested for political campaigns.

Mr Damian Collins, chairman of the House of Commons digital, culture, media and sport committee, wrote to Mr Zuckerberg asking for his own account of "this catastrophic failure of process".

The request was made as part of the committee's ongoing investi-gation into fake news, which saw its members last month visit Washington for hearings with officials from Facebook and Twitter.

But it follows allegations that data from up to 50 million Facebook users was harvested by British company Cambridge Analytica for use in the election campaign of US President Donald Trump in 2016.

"Following material published in the UK Guardian and The New York Times over the past few days, the committee would like to request that you appear before us to give oral evidence," Mr Collins wrote.

The committee has repeatedly asked Facebook about how companies acquire and hold on to users' data, and whether data had been taken without their consent. Mr Collins set Mr Zuckerberg a deadline of March 26 to reply.

Facebook and Cambridge Analytica both maintain that they have not acted improperly.

Mr Zuckerberg and Facebook COO Sheryl Sandberg have remained conspicuously silent since the Cambridge Analytica story broke at the weekend. Analysts say the scandal has raised the prospect of an expansion of privacy protections across the globe.

"The fact of the matter is that Facebook lost control of the data and wasn't adequately monitoring what third parties were doing," said Mr Scott Vernick, an expert in privacy and data security at Philadelphia law firm Fox Rothschild.

The mess engulfing the social media giant appears to be deepening.

Facebook's chief security officer Alex Stamos is quitting over disputes with other top executives over how aggressively to confront the company's security problems, The New York Times reported on Monday.

Facebook scheduled an open meeting for all employees yesterday morning (US time) to let them ask questions about the scandal, according to an internal calendar invitation seen by The Verge.

AGENCE FRANCE-PRESSE, REUTERS, WASHINGTON POST