The news comes on the heels of the revelation that Facebook hired the Republican-linked firm Definers Public Affairs to conduct campaign-style opposition research into organizations Soros had backed.
The people with knowledge of Sandberg's email asked for anonymity because they weren't authorised to discuss the message and feared retribution.
Facebook's chief operating officer Sheryl Sandberg has been accused of being directly involved in the company's (once) covert investigation into billionaire George Soros. "Facebook must immediately release any emails and any research about targeting the Freedom from Facebook coalition or any member organisations". Just two weeks ago, Sandberg denied knowing about a separate, later effort to push stories about Soros by a political firm hired by the social media giant.
Author of the feminist bestseller "Lean In", Sandberg also drew attention in 2015 after the sudden death of her husband David Goldberg at age 47.More news: Engagement ring lost moments before proposal found by police
Definers helped spread stories about other tech companies in an apparent effort to deflect attention from Facebook, and it provided material to reporters that aimed to connect Soros to anti-Facebook groups. It is unclear what, if any, involvement Sandberg had in that ultimate response to Soros.
Sandberg reportedly wanted to know if Soros, who publicly criticized Facebook, was shorting the company's stock.
Facebook has stumbled from one mess to another this year as it grapples with continuing fallout from Russia's use of the platform to interfere in the 2016 USA presidential election, the Cambridge Analytica scandal in which user data was harnessed in a bid to help candidate Donald Trump, and a huge security breach involving millions of accounts. The email was forwarded to other senior communications and policy staff.
Some have called on Sandberg to be fired.
Schrage taking the hit for the controversy was seen by some as convenient, since he had said he was leaving the social network after working there for more than a decade.
Civil rights group Color of Change on Friday said Facebook has agreed to release an update on the status of its civil rights audit and early findings by the end of the year.More news: South Africa World Cup victor Drotske shot during Pretoria robbery
Robinson said that while meeting with Sandberg, she denied hiring Definers or directing the firm's research.
"Responsibility for these decisions rests with leadership of the Communications team", Schrage said.
Roger Kay, an analyst and consultant at Endpoint Technologies Associates who follows the tech sector, said the moves by Facebook and Sandberg showed "extraordinarily poor judgment" from a corporate governance view.
"We were not satisfied with that answer", he said.More news: Fury and Wilder draw in spectacular heavyweight title clash