Facebook Inc. Chief Executive Officer Mark Zuckerberg is getting personally involved in an investigation into allegations of bias in the way the company highlights important news on its social network.

The CEO will host open discussions with conservative leaders and other politicians about how the company can avoid appearing biased, he said in a Facebook post.

“This week, there was a report suggesting that Facebook contractors working on Trending Topics suppressed stories with conservative viewpoints,” Zuckerberg, 31, wrote in a post on Thursday. “We take this report very seriously and are conducting a full investigation to ensure our teams upheld the integrity of this product.”

While Zuckerberg said the company found no evidence the report is true, it will take steps to address problems if the probe uncovers anything against its principles.

Earlier Thursday, Facebook released guidelines showing that methods it uses to determine trending news topics rely heavily on human input and company rules, contradicting some of its earlier statements that the system is mostly machine-based.

Tom Stocky, Facebook’s executive in charge of the team, on Monday  said the company doesn’t “insert stories artificially” into the trending topics feature, while the documents say that news topics can be inserted by human editors.

Stocky also said the guidelines don’t permit the prioritization of one news outlet over another; the documents show Facebook checks its news against 10 news organizations to measure if a trending topic is legitimate.

Facebook released the internal documents after they were cited in a report by the Guardian. The company has been embroiled in a dispute about whether it suppresses conservative viewpoints in the trending topics feature, set off by a report about internal bias this week by Gizmodo. Though the company denies the report, which cited anonymous former contract workers, scrutiny of the social network’s process has been increasing, with U.S. Senator John Thune sending Zuckerberg a letter inquiring about the allegations and requesting answers by later this month.

The guidelines are “checks and balances” to help Facebook display stories that are actually newsworthy, rather than just popular on its site, helping it build a better product, said Justin Osofsky, vice president of Facebook’s global operations.

“Facebook does not allow or advise our reviewers to systematically discriminate against sources of any political origin, period,” Osofsky said in a statement. “The intent of verifying against news outlets is to surface topics that are meaningful to people and newsworthy.”