Mark Zuckerberg defends Facebook in "trending" bias controversy

With more than 1.6 billion users, Facebook has become a key player in the distribution of news worldwide. But now CEO Mark Zuckerberg is battling claims that the site doesn't play fair.

In an online post, Zuckerberg defended his company against accusations of political bias, saying Facebook does not censor conservative topics. "We have rigorous guidelines that do not permit the prioritization of one viewpoint over another," he wrote.

Zuckerberg said he will be reaching out to conservative leaders in the wake of the controversy. "In the coming weeks, I'll also be inviting leading conservatives and people from across the political spectrum to talk with me about this and share their points of view. 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," he wrote.

His decision to personally address the controversy comes after Facebook announced it was launching its own investigation into anonymous claims, published by the tech news site Gizmodo, that workers put a liberal spin on which stories were highlighted on the social network's "Trending Topics" list.

At issue is the process by which Facebook decides what's "trending." The Guardian newspaper obtained a copy of Facebook's internal guidelines Thursday, revealing a range of circumstances in which workers may evaluate and either add or reject stories on the list, reports CBS news correspondent Jan Crawford.

"They can go in and inject new topics, they can delete topics that are duplicate or inappropriate, they can blacklist things they think shouldn't be in trending topics," said Guardian reporter Sam Thielman. "I think the guidelines themselves are very straightforward and they try very hard to maintain objectivity."

Zuckerberg said the company's investigation into the bias claims has found "no evidence that this report is true."

But this week, the chairman of the Senate Commerce Committee, Republican Sen. John Thune, called for a congressional inquiry.

"Consumers have rights and we want to make sure we're protecting consumer's rights, and that businesses aren't in fact engaging in any kind of deceptive practice," Thune said.

Zuckerberg said he wants to meet with "leading conservatives and people from across the political spectrum" to discuss how Facebook can remain "as open as possible."

"They have a history of trying to maintain good public relations and they're going to do it," Thune said. "My questions would be whether it affects internal operations. I suspect it won't."After the internal documents were leaked, Facebook made its internal guidelines public. The company is trying to emphasize that while there is a team of editors vetting content, what's trending is primarily generated by those computer algorithms.