Facebook admitted on Wednesday that a top executive hired a public relations firm to attack George Soros and undermine critics by publicizing their association with the billionaire Jewish philanthropist.

Elliot Schrage, Facebook’s outgoing head of communications and policy, took responsibility for hiring Definers Public Affairs in a memo first reported by TechCrunch and subsequently published as a blog post on the eve of the US Thanksgiving holiday.

Both Mark Zuckerberg and Sheryl Sandberg had disavowed knowledge of the firm’s hiring in comments to the press.

“Did we ask them to do work on George Soros?” the memo reads. “Yes.”

Schrage explained that the work on Soros was two-pronged. After Soros characterized Facebook and Google as a “menace to society” in a speech at the World Economic Forum in Davos in January 2018, Facebook asked Definers to perform research because it “wanted to determine if he had any financial motivation”.

Later, when a new organization called Freedom From Facebook emerged as a critic of the company’s privacy practices, Definers “learned that George Soros was funding several of the coalition members”, Schrage wrote, and “prepared documents and distributed these to the press to show that this was not simply a spontaneous grassroots movement”.

The work on Soros is sensitive because of the peculiar role that the Hungarian-born investor and philanthropist plays in rightwing conspiracy theories and among antisemites. Soros has long funded liberal and pro-democratic causes, making him a target of the right, the fringes of which have recast Soros as a modern day embodiment of the classic antisemitic trope of a secretive Jewish cabal pulling the strings on world affairs.

The very rude elevator screamers are paid professionals only looking to make Senators look bad. Don’t fall for it! Also, look at all of the professionally made identical signs. Paid for by Soros and others. These are not signs made in the basement from love! #Troublemakers — Donald J. Trump (@realDonaldTrump) October 5, 2018

Antisemitic and baseless conspiracy mongering about Soros has become more mainstream in recent years, with mainstream Republicans including president Donald Trump invoking his name in order to undermine critics and protesters.

The Schrage memo does not include any apology for Definer’s or Facebook’s work on Soros. Indeed, Schrage defended the idea of a company using a political consultancy to perform opposition research on critics, writing: “Some of this work is being characterized as opposition research, but I believe it would be irresponsible and unprofessional for us not to understand the backgrounds and potential conflicts of interest of our critics.”

In a comment appended to the memo, Sandberg admitted that she had “received a small number of emails where Definers was referenced”.

Addressing the widespread criticism that the work on Soros was based on an antisemitic trope, she wrote: “I also want to emphasize that it was never anyone’s intention to play into an antisemitic narrative against Mr Soros or anyone else. Being Jewish is a core part of who I am and our company stands firmly against hate. The idea that our work has been interpreted as antisemitic is abhorrent to me — and deeply personal.”

Mark Zuckerberg has said he knew nothing about the PR firm. Photograph: Gérard Julien/AFP/Getty Images

Patrick Gaspard, the president of Soros’s philanthropic body, the Open Society Foundation, lambasted Facebook engagement with antisemitic tropes last week, writing in a letter to Sandberg: “The notion that your company, at your direction, actively engaged in the same behavior to try to discredit people exercising their first amendment rights to protest Facebook’s role in disseminating vile propaganda is frankly astonishing to me.

Gaspard appeared unimpressed by Facebook’s release of the memo on Wednesday, tweeting: “So @facebook decides to drop a turkey on Thanksgiving eve, with admission that Definers was tasked by company leadership to target and smear George Soros because he publicly criticized their out of control business model. Sorry, but this needs independent, congressional oversight.”

Tim Miller, Definers’ Silicon Valley lead, has defended its research, which he said was “factually based”, adding that he was “disgusted by the rise of antisemitism including people who have falsely targeted Soros”.

