Singapore authorities Friday ordered Facebook to correct an article on a fringe news site containing "scurrilous accusations" of election rigging, ramping up their use of a controversial law against misinformation.

The social media giant, which has previously expressed concerns about the legislation, did not respond to requests for comment and the article was still on the site without any changes.

The order is a test of the new law, which gives ministers powers to tell platforms to put warnings next to posts authorities deem false, but which activists fear could be used to curb free speech.

On Thursday authorities ordered Alex Tan, who runs anti-government website the States Times Review, to put up a correction next to a November 23 post on elections.

But Tan -- who is based overseas -- refused, saying he is an Australian citizen and would not comply with requests from a "foreign government".

A body overseeing the law then said it had ordered Facebook to put up a "correction notice" by the article, which would link to a statement on the government's own fact-checking site.

That statement said that Tan's article, which claims elections are rigged in Singapore to ensure the ruling party stays in power, contained "false statements of fact" and "made scurrilous accusations".

Singapore used the law for the first time Monday, ordering opposition party member Brad Bowyer to correct a Facebook post authorities said could "smear the reputation" of two state investment funds.

Bowyer -- a naturalised Singapore citizen originally from Britain -- immediately complied.

Facebook, a major investor in Singapore, has its Asia headquarters in the city-state and last year announced plans to build a $1 billion data centre there.

Despite the concerns, Singapore's government, which regularly faces criticism for curbing civil liberties, insists the legislation is necessary to stop the spread of damaging falsehoods online.