Walden is chairman of the Energy and Commerce Committee and Pallone is the panel’s top senior Democrat. Their statement comes a day after Zuckerberg told CNN he would be “happy” to testify before Congress.

Walden and Pallone asked for responses by next week to a series of questions, including whether Facebook is aware of any other instances in which a third-party app developer used or shared Facebook user data improperly.

It’s far from certain what action, if any, the Republican-led Congress and the Trump administration might take against Facebook, but the company will almost certainly oppose any efforts to regulate it or the technology business sector more broadly.

Their call represents the first official request from a congressional oversight committee for Zuckerberg’s appearance amid demands by lawmakers that Facebook explain reports that Cambridge Analytica harvested the data of more than 50 million Facebook users to sway elections.

The data was gathered through a personality test app called “This Is Your Digital Life” that was downloaded by fewer than 200,000 people. 

But participants unknowingly gave researchers access to the profiles of their Facebook friends, allowing them to collect data from millions more users.

Congress isn’t alone in its interest in the Facebook-Cambridge Analytica affair.

US special counsel Robert Mueller is now scrutinising the connections between Cambridge Analytica and US President Donald Trump’s campaign, which it helped support.

Mueller’s investigators have asked former campaign officials about the Trump campaign’s data operations, particularly how it collected and utilised voter data in battleground states.

The company, funded in part by Trump supporter and billionaire financier Robert Mercer, paired its vault of consumer data with voter information. 

The Trump campaign paid the firm nearly US$6 million during the 2016 election, although it has since distanced itself. 

Other Republican clients of Cambridge Analytica included Republican Senator Ted Cruz’s failed presidential campaign and Ben Carson, the famed neurosurgeon who also ran unsuccessfully for president in 2016.

And state attorneys general in Massachusetts, New York and New Jersey have also opened investigations into the case. Some have also rallied to a movement that urges people to delete their Facebook accounts entirely.

Fury has also been directed at Cambridge Analytica in Europe. 

Germany’s justice minister said she is calling in Facebook’s European leadership to explain the scandal involving data mining firm Cambridge Analytica and detail whether German users’ data were affected.

Katarina Barley said Thursday she has invited Facebook officials to a meeting at her ministry next week, though the exact date has yet to be determined.

Barley, who is also responsible for consumer protection, says she wants “comprehensive information” from Facebook, including on “whether German user accounts are affected, and what Facebook plans to do to prevent a repeat of such cases.”

Britain’s culture secretary, Matt Hancock, has also criticised the company, and said Zuckerberg’s promises to change the social media giant don’t go far enough.

Zuckerberg has apologised for weaknesses in the social network’s policies that enabled an app to gain access to the personal information of 50 million users without their consent. He outlined steps to protect user data and said companies have a responsibility to act.

But Hancock said Thursday that the UK Parliament and society should set the rules as to what the appropriate for privacy and innovation – not any one company.

Hancock says “that’s the approach that we are taking. The big tech companies need to abide by the law and we are strengthening the law.”