Facebook has blocked Australian users from sharing or viewing news content on the platform, causing much alarm over public access to key information.

It comes in response to a proposed law which would make tech giants pay for news content on their platforms.

Australians on Thursday woke up to find that Facebook pages of all local and global news sites were unavailable.

Several government health and emergency pages were also blocked - something Facebook later asserted was a mistake.

Those outside of the country are also unable to read or access any Australian news publications on the platform.

The Australian government has strongly criticised the move, saying it demonstrated the "immense market power of these digital social giants".

Treasurer Josh Frydenberg said the ban on news information had a "huge community impact". About 17 million Australians visit the social media site every month.

He said the government was committed to passing the law, and "we would like to see them [Facebook] in Australia.

"But I think their actions today were unnecessary and wrong," he added.

Google and Facebook have fought the law because they say it doesn't reflect how the internet works, and unfairly "penalises" their platforms.

However, in contrast to Facebook, Google has in recent days signed payment deals with three major Australian media outlets.

Facebook's action came just hours after Google agreed to pay Rupert Murdoch's News Corp for content from news sites across its media empire.

Why is Facebook doing this?

Australian authorities had drawn up the laws to "level the playing field" between the tech giants and struggling publishers over profits. Of every A$100 (£56; $77) spent on digital advertising in Australian media these days, A$81 goes to Google and Facebook.

But Facebook said the law left it "facing a stark choice: attempt to comply with a law that ignores the realities of this relationship, or stop allowing news content on our services in Australia".

"With a heavy heart, we are choosing the latter," it said in a blog post.