Facebook is rolling out its new tool against fake news.
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SEE ALSO:Facebook is cracking down on hoaxes in your News Feed。

The feature, announced in December is the result of collaboration with "third-party fact-checking organisations."。

Designed to combat to the spread of misinformation on the platform, it warns users when they try to post fake stories.。

The fact-checker is working for some U.S.-based users who tried to share a story that falsely asserted thousands of Irish people were brought to the United States as slaves.。

The story entitled "The Irish slave trade -- the slaves that time forgot" was published by the Rhode Island blog Newport Buzz and widely shared ahead of St Patrick's Day on 17 March.
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Attempts to share the story triggered a red alert in the pop up window stating that the article has been disputed by Snopes.com and。 the Associated Press。the Associated Press。

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Clicking on it would open a second pop-up with more information:
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"Sometimes people share fake news without knowing it. When independent fact-checkers dispute this content, you may be able to visit their websites to find out why,” it reads. “Only fact-checkers signed up to Poynter’s non-partisan code of principles are shown.”Mashable Light SpeedWant more out-of-this world tech, space and science stories?Sign up for Mashable's weekly Light Speed newsletter.   。Sign up for Mashable's weekly Light Speed newsletter.
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It also links to Facebook's official help page and to the debunking articles from AP and Snopes.com. 。

If you ignore the warning, another pop-up asserts that the article's accuracy is "disputed by multiple, independent fact-checkers".。

If you proceed to publish the article a red box still shows up in the timeline: 。

The feature was announced in December 2016 but this appears to be the first time people have noticed it on a story that went viral.。Mashable。

attempted to post the story using a device in London, but the red alert did not show up. 。

Facebook's help centre page entitled 'How is news marked as disputed on Facebook' confirms that the feature isn't available to everyone yet. 。

Some Trump supporters have been critical of the tool, questioning its veracity.
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Paul Joseph Watson, editor-at-large of Infowars, criticised the inclusion of Snopes in Facebook's list of independent fact-checkers. 。

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Liam Hogan, a librarian and historian based in Ireland, said Trump supporters were "losing their minds" about the red alert:
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Other Trump fans or right-wing bloggers took to Twitter to assert that the Irish slave trade was real and Facebook was committing "Pre-Thoughtcrime": 。

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