Facebook chief executive Mark Zuckerberg will hold meetings with some US lawmakers on Monday, a day before he is due to appear at Congressional hearings in connection with a political consultancy's use of customer data, two congressional aides said.
The meetings on Capitol Hill are expected to continue through Monday afternoon and include some members of committees before whom Mr Zuckerberg is due to testify, said the aides.
Facebook declined to comment.
Mr Zuckerberg is scheduled to appear before a joint hearing of the US Senate Judiciary and Commerce committees on Tuesday and the US House Energy and Commerce Committee on Wednesday.
Facebook has been under fire in recent weeks after it said that the personal information of up to 87 million users, mostly in the United States, may have been improperly shared with political consultancy Cambridge Analytica.
A Facebook spokesman said on Sunday that the company plans to begin telling affected users on Monday.
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London-based Cambridge Analytica, which has counted US President Donald Trump's 2016 campaign among its clients, has disputed Facebook's estimate of the number of affected users.
Mr Zuckerberg is expected in his testimony to recognise a need to take responsibility and acknowledge an initial failure to understand how many people were affected, a person briefed on the matter, who asked for anonymity, said on Sunday.
Mr Zuckerberg said last week that he accepted blame for the data leak, which has angered users, advertisers and politicians, while also saying he was still the right person to lead the company he founded.
On Friday, Facebook backed proposed legislation requiring social media sites to disclose the identities of buyers of online political campaign ads and introduced a new verification process for people buying "issue" ads.
The steps are designed to deter the kind of election interference and online information warfare that US authorities have accused Russia of pursuing, Mr Zuckerberg said on Friday. Moscow has denied the allegations.
In February, US Special Counsel Robert Mueller charged 13 Russians and three Russian companies with interfering in the 2016 US presidential election by sowing discord on social media.
Mr Zuckerberg, on the call with reporters, said Facebook should have done more to audit and oversee third-party app developers like the one hired by Cambridge Analytica in 2014.