Philanthropist George Soros has called on Facebook to initiate an independent, internal investigation of its lobbying and public relations work.
The call comes after the New York Times published a report claiming the company had hired an opposition research firm to discredit critics by linking them to Soros, a frequent target of conservatives and anti-Semitic vitriol from the far right.
"These efforts appear to have been part of a deliberate strategy to distract from the very real accountability problems your company continues to grapple with," wrote Patrick Gaspard, the president of the Open Society Foundations, a philanthropic organisation founded by Soros.
According to the New York Times report, Sandberg oversaw an aggressive lobbying campaign to counter the public backlash against the company, after an onslaught of scandals involving Russian misinformation, privacy violations and the viral spread of hateful messages.
The company adopted a public relations strategy akin to campaign-style opposition research, the report said, in which others were attacked, such as Google and Apple, to deflect blame. Sandberg also wielded her high-ranking position at Facebook to personally appeal to lawmakers in Washington and state attorneys general, the report said, in the hope of curtailing regulations and investigations targeting the social network.
Facebook hired a Republican opposition research firm to discredit activists critical of the social network, according to the report. Some of the efforts linked the activists to Soros, the report said. The firm circulated a document to reporters that "cast Mr Soros as the unacknowledged force behind what appeared to be a broad anti-Facebook movement", according to the New York Times.
The firm cited in the report, Definers Public Affairs, did not immediately respond to a request for comment from the Washington Post.
Facebook told the Washington Post: "It is wrong to suggest that we have ever asked Definers to pay for or write articles on Facebook's behalf - or to spread misinformation."