Facebook co-founder and CEO Mark Zuckerberg met with US President Donald Trump and members of Congress Thursday, as Facebook faces a raft of regulatory and legal issues concerning competition, digital privacy, censorship and transparency.

During one-on-one meetings with lawmakers, Zuckerberg reportedly faced calls to break up Facebook, the world's biggest social network with 2.5 billion users.

Republican Senator Josh Hawley told reporters he met with Zuckerberg and "challenged him to show that Facebook is serious about bias, privacy and competition."

The senator said he told Zuckerberg to sell WhatsApp and Instagram "to prove you're serious about protecting data privacy," adding that Zuckerberg told him "it wasn't a good idea."

Read more: Opinion: Facebook's Zuckerberg's mea culpa is not enough

Is Facebook too big?

Hawley criticized Facebook for moving personal data from properties such as WhatsApp and Instagram to the core Facebook platform.

The messaging service WhatsApp and picture-sharing app Instagram are under Facebook's umbrella of services, and are among around 70 companies that Facebook has acquired.

Read more: Shall I stay or shall I go now? The Facebook conundrum

This has raised concern about its market power stifling competition and the company's control over massive amounts of user data.

US federal and state antitrust agencies are exploring anti-competitive actions potentially committed by Facebook, and members of Congress are debating privacy legislation that could limit the ability of companies like Facebook, Google, Amazon and Apple to collect and make money from users' personal data.

'More transparency'

Senate Democrat Mark Warner, who is leading a push in Washington for more digital legislation, told Fox Business Network that he was not ready to dismantle Facebook.

Read more: Opinion: Saying sorry isn't enough, Mark Zuckerberg

"But I do think we need a lot more transparency. We need to have privacy rights protected. We need to increase competition with things like data portability and interoperability," he said.

Two months ago, the US Federal Trade Commission hit Facebook with a record $5 billion (€ 4.5 billion) fine  for data protection violations over the Cambridge Analytica data scandal. The settlement called for new privacy controls and better oversight at the social network. 

Zuckerberg also met with President Trump on Thursday who wrote on Twitter that the two had a "nice meeting." No details were provided from the White House or Facebook about exactly what was discussed at the meeting.

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wmr/kl (AP, Reuters, AFP)