The head of George Soros grant-making network has called for an investigation with “independent, congressional oversight” into Facebooks operations after the social network confirmed it had hired a PR firm to make claims about the billionaire philanthropist.

The statement by Patrick Gaspard, president of Open Society Foundations, is the first statement from anyone associated with Soros, who funds a variety of liberal causes but typically stays away from the spotlight. It comes following a statement by Facebooks departing communications chief Elliot Schrage that confirmed the company had hired PR firm Definers to investigate Soros links to the Freedom from Facebook campaign.

Schrages statement has led to further criticism of Facebook, with many industry experts describing it as an attempt to offer up the already-departing Schrage as a scapegoat. The timing of the statement, just before most Americans departed work for the long Thanksgiving weekend, has also drawn criticism.

The statement has reportedly angered “many people” within Facebook, with several angry that CEO Mark Zuckerberg and chief operating officer Sheryl Sandberg are attempting to distance themselves from the controversy. Sandberg in particular has been a target for ire, given her previous reputation for closely managing Facebooks media strategy.

The New York Times has followed up on its initial report into Facebooks use of Definers with further claims, including that the PR firm engaged in a campaign against chip-maker Qualcomm on the social networks behalf. The report also claims that Definers set up a website promoting the idea that Apple CEO Tim Cook was planning a presidential bid, in order to undermine Apples relationship with the Trump administration.