Google is wading into the battle against online fake news and adding a fact check to its search results.

The Californian tech giant announced on Friday that it is rolling out globally a feature in its search and news results that will assess the authenticity of information shown.

Google isn't doing this fact-checking itself: Instead, it's relying on respected independent fact-checking organisations like PolitiFact and Snopes to provide the info.

So if you search for "27 million people enslaved," for example, a fact-check box will appear at the top of the search results, telling you that PolitiFact says US Senator Bob Corker's claim that 27 million people are trapped in modern slavery is "mostly true."

Or in News results, it will stick a "Fact Check" option alongside the standard stories providing more details.

In a blog post, Google cautions that this isn't Google passing judgment on a particular claim: "This information won’t be available for every search result, and there may be search result pages where different publishers checked the same claim and reached different conclusions. These fact checks are not Google's and are presented so people can make more informed judgments. Even though differing conclusions may be presented, we think it's still helpful for people to understand the degree of consensus around a particular claim and have clear information on which sources agree."

It adds: "As we make fact checks more visible in Search results, we believe people will have an easier time reviewing and assessing these fact checks, and making their own informed opinions."

The feature was built by Jigsaw, a think tank/ideas lab owned by Google's parent company Alphabet. It was previously available in certain countries in Google News — but it is now being rolled out globally, in both Google News and the main Google Search.

It comes at a time of acute anxiety among much of the media and tech industry over the threat of "fake news" and misinformation online. Facebook has come under intense criticism in the aftermath of the US presidential election in November 2016 over the spread of malicious false news stories on its platform, and has pledged to do more to combat it.

Facebook recently introduced a fact check feature of its own that would flag if an article being shared is disputed by fact checkers. And on Thursday, the social network said it would provide tips to education to its users on how to spot fake news (including investigating the source and seeing if the photos look manipulated).

Google has also tried to tackle fake news-peddlers by kicking them off its ad network, starving them of advertising revenue.