Last week the New York Times broke with its long tradition of being Apple’s press office to break some actual news. It discovered that Facebook had hired Definers Public Affairs to push negative stories about Facebook's critics, including the philanthropist George Soros.

Facebook denied doing it but waited until Thanksgiving to admit it was true. The idea is that the US shuts down over Thanksgiving so no one will read the news.

Facebook's communications and policy chief, Elliot Schrage, said in a memo posted Wednesday that he was responsible for hiring the group, and had done so to help protect the company's image and conduct research about high-profile individuals who spoke critically about the social media platform.

Schrage will be leaving the company, a move planned before the memo was released.

Facebook fired Definers last week.

"Did we ask them to do work on George Soros?" Schrage wrote in the memo, a draft of which had circulated online earlier in the week.

"Yes. I'm sorry I let you all down. I regret my own failure here." This is a change from just a few days ago, when Facebook wrote on 15 November that the Times report was full of “inaccuracies."

The same day, Sheryl Sandberg, the company's chief operating officer, posted on her Facebook page that she had no idea the company had hired Definers.