Facebook is deleting the name of the alleged whistleblower who triggered Donald Trump's impeachment inquiry.
The company says any mention of it violates its "coordinating harm policy", which prohibits material that could identify a "witness, informant, or activist".
It says it will revisit the decision if the name is widely published in the media or used by public figures in debate.
The policy is not new - Facebook has been removing the person's name for days.
On Friday, the name was widely circulated on Twitter - with the US president's son, Donald Trump Jr, writing a post that included a link to an article which identified the alleged whistleblower.
The whistleblower claims Mr Trump abused the power of his office to "solicit interference from a foreign country" in the 2020 US election.
Some of the stories identifying the person came from the conservative news site Breitbart, which Facebook counts as one of its news partners in a newly launched news section on its app.
However, the company said it was also removing identifying posts on the whistleblower from Breitbart.
In a statement, Twitter said it prohibits the sharing of "personally identifiable information about any individual, including the alleged whistleblower".
But the company's policy on such information does not consider a person's name to be private information in the same way as a person's address, contact information or medical records.
This is not the first time Twitter and Facebook have gone in opposite directions.
Last week, Twitter said it was banning all political ads - but Facebook continues to defend running paid ones, even if they are false, as a free speech priority.
Members of Congress from both parties have historically backed laws to protect the identity and careers of people who anonymously accuse government officials of wrongdoing.
President Trump has previously said "the impeachment hoax should be ended immediately" and claimed "there is no case, except against the other side".
© Sky News 2019