UPDATE 1-Facebook to prioritize 'trustworthy' news sources

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SAN FRANCISCO, Jan 19 (Reuters) - Facebook Inc will begin to prioritize "trustworthy" news outlets on its stream of social media posts as it works to combat "sensationalism" and "misinformation," Chief Executive Mark Zuckerberg said on Friday.

The company, which has more than 2 billion monthly users, said it will use surveys to determine rankings on how trustworthy news outlets are.

Zuckerberg outlined the shakeup in a post on Facebook, saying that starting next week the News Feed, the company's centerpiece product, would prioritize "high quality news" over less trusted sources.

"There's too much sensationalism, misinformation and polarization in the world today," Zuckerberg wrote.

"Social media enables people to spread information faster than ever before, and if we don't specifically tackle these problems, then we end up amplifying them," he wrote.

At the same time, Zuckerberg said the amount of news overall on Facebook would shrink to roughly 4 percent of the content on the News Feed from 5 percent currently.

Facebook has had a stormy relationship with news organizations, especially those with strong political leanings. In 2016, Republican U.S. lawmakers expressed concern that Facebook was suppressing news stories of interest to conservative readers.

Last week, Zuckerberg said the company would change the way it filters posts and videos on News Feed to prioritize what friends and family share.

(Reporting by David Ingram; Editing by Andrew Hay and Leslie Adler)