Facebook has expressed concern after it was ordered by Singapore to block access to a news site's page.
Singapore said the fringe site States Times Review had broken a newly introduced "fake news" law and repeatedly conveyed "falsehoods".
Facebook said it was "legally compelled" to comply with the order to block access from Singapore, but said the order was "deeply concern[ing]".
It added that the directive could "stifle freedom of expression".
The law - known as the Protection from Online Falsehoods and Manipulation bill (POFMA) - came into effect in October.
The Singapore government has said it needs strict laws given the potential for fake news to incite racial and religious disharmony, and that it needs the power to act swiftly to halt the viral spread of falsehoods.
A Facebook company spokesman said in a statement to the BBC: "We believe orders like this are disproportionate and contradict the government's claim that POFMA would not be used as a censorship tool."
"We've repeatedly highlighted this law's potential for overreach and we're deeply concerned about the precedent this sets for the stifling of freedom of expression in Singapore."
What did the page post?
Authorities said the States Times Review (STR) had in January put up a Facebook post which "falsely claimed that Singapore had run out of face masks". The article was written in relation to the current coronavirus situation, which has seen many in Singapore scrambling to buy face masks.
Singapore, which has reported dozens of virus cases, has always said it has enough supplies and has made sufficient preparations to handle the outbreak.
It ordered STR to issue a correction direction - a notice stating that the information put up was false. However, these correction directions were ignored.
The Ministry of Communications and Information on 15 February ordered STR to carry a notice saying that it was a Declared Online Location. This meant anyone who visited the page would be "warned that [it] has a history communicating falsehoods".
STR did not carry out the notice. Authorities said that it instead "changed the vanity URL of the page", leading the ministry to instead issue a further directive to Facebook to block access to site for Singapore-based users.
Minister for Communications and Information S Iswaran said there was a particular need to "act swiftly" against falsehoods in light of the virus outbreak.
"If we don't, these falsehoods can cause anxiety, fear and even panic," he had said.
The States Times Review page has received at least three correction directions since November last year.
Facebook has previously added a correction notice to an STR post, after being ordered to do so. The notice said Facebook was "legally required to tell you that the Singapore government says this post has false information".
The editor of the site, Australian citizen Alex Tan, had said last year that he would "not comply with any order from a foreign government".
What would have happened if Facebook had not complied?
POFMA allows the government to order online platforms to remove and correct what it deems to be false statements that are "against the public interest".
Under POFMA, Facebook would have been found guilty of an offence if it had not complied with the government's orders.
It would be liable on conviction to a fine not exceeding S$20,000 ($14,378; £11,061) a day, up to a total of S$500,000.
Facebook's Asia Pacific headquarters are based in Singapore. It has also invested more than S$1bn to build a data centre in Singapore, which is due to open in 2022.
What has been said about the fake news law?
Singapore has always exercised tight control of its media. It ranks 151 out of 180 countries in this year's World Press Freedom Index.
Critics have said the law threatens freedom of expression. Amnesty International said it would "give authorities unchecked powers to clamp down on online views of which it disapproves".
But Singapore's law minister said free speech "should not be affected by this bill", which was aimed only at tackling "falsehoods, bots, trolls and fake accounts".
It has argued that the law safeguards against abuse of power by allowing judicial reviews of government orders.