Facebook on Thursday emphasized that it does not permit its employees to block news stories from its "Trending Topics" list based on political bias, amid recennt reports that the social media superpower selects what news it displays. Gizmodo on Monday reported that a former Facebook employee said workers "routinely suppressed news stories of interest to conservative readers" while "artificially" adding other stories to the trending list.

Facebook said that the Trending Topics team is governed by a set of guidelines meant to ensure a high-quality product, consistent with Facebook’s commitment to being a platform for people of all viewpoints.

"Our goal has always been to deliver a valuable experience for the people who use our service. The guidelines demonstrate that we have a series of checks and balances in place to help surface the most important popular stories, regardless of where they fall on the ideological spectrum. Facebook does not allow or advise our reviewers to discriminate against sources of any political origin, period," Justin Osofsky, vice president of global operations at Facebook, wrote in a blog post.

The blog post went on to explain how certain topics emerge in Facebook users' trending feeds. Potential trending topics are identified by an algorithm, or formula, Facebook said, then reviewed by a "Trending Topics" team.

Mark Zuckerberg, co-founder and chief executive of the social media site, also took to Facebook on Thursday evening to say he plans to talk with leading conservatives in coming weeks.

"I want to have a direct conversation about what Facebook stands for and how we can be sure our platform stays as open as possible," the statement said.