Facebook's COO Sheryl Sandberg released a separate statement, saying she did not remember a firm called Definers.
Facebook admitted hiring public relations firm Definers in 2017, and asked it to look into philanthropist George Soros' involvement in the "Freedom from Facebook" campaign.
"Freedom from Facebook" is an advocacy group that seeks to break down the Mark Zuckerberg-run company.
In a statement on November 21 Facebook's outgoing Head of Communications and Policy Elliot Schrage shared details of the work Definers did for the company.
Schrage took responsibility for hiring the firm, saying he was aware of the decision and approved it.
Investor and philantropist George Soros had in January 2018 called Facebook a "menace to society" in a speech at the World Economic Forum held in Davos.
"We had not heard such criticism from him before and wanted to determine if he had any financial motivation. Definers researched this using public information," Schrage said.
The company even admitted to sending documents to the press that hinted at links between Soros and Freedom and Facebook, to prove that it is not a grassroots movement.
Schrage said of the work that was done is being called "opposition research". But he added that it would be "irresponsible and unprofessional" to not try and understand the background of the social media platofrm's critics.
The company denied asking Definers to create or disseminate fake news. Facebook is now looking into the work Definers has done for the company.
Facebook's Chief of Operations (COO) Sheryl Sandberg released a separate statement, saying she did not remember a firm called Definers.
Sandberg also denied accusations that Facebook was anti-Semitic by investigating George Soros, who is Jewish."It was never anyone’s intention to play into an anti-Semitic 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 anti-Semitic is abhorrent to me — and deeply personal," Sandberg clarified.