Facebook admits human role in news operation but denies Left-wing bias
Facebook has admitted that humans are involved in determining the content of its trending news section but denied accusations of Left-wing political bias.
In a statement Justin Osofsky, vice president of global operations, said there were a "series of checks and balances" in place to make sure stories appeared "regardless of where they fall on the ideological spectrum".
"Topics that are eligible to appear in the product are surfaced by our algorithms, not people. This product also has a team of people who play an important role in making sure that what appears in Trending Topics is high-quality and useful."
He added: "Facebook does not allow or advise our reviewers to discriminate against sources of any political origin, period."
However, internal documents leaked to the Guardian showed a team of news editors was able to "inject" stories.
The editors were even given a specific example of what to inject - stories relating to the Black Lives Matter protest group.
Earlier his week technology website Gizmodo claimed Facebook had failed to publish popular stories about conservative issues.
Independent contractors who worked on the Trending Topics team said those stories related to a high profile conservative political conference in the US and former Republican presidential candidate Mitt Romney.
Tom Stocky, who tuns the Trending Topics section, said there was "no evidence" to back that up.
He said: “We take these reports extremely seriously and have found no evidence that the anonymous allegations are true.
"There are rigorous guidelines in place for the review team to ensure consistency and neutrality."
Last month, Mark Zuckerberg, the Facebook founder and chief executive, publicly criticisied presumptive Republican presidential nominee Donald Trump over his plan to build a wall on the US-Mexican border.