A person claiming to speak for activist hacker group Anonymous on Thursday threatened to "go to war" with Singapore by attacking its financial infrastructure to protest recent licensing rules for news websites.
"We demand you reconsider the regulations of your framework or we will be forced to go to war with you," a male voice said as a person hiding behind a mask appeared in a clip posted on video-sharing site YouTube.
"Everytime you deprive a citizen his right to information, we will cause you financial loss by aggressive cyber intrusion," said the speaker.
The video was taken off YouTube by early evening after Singapore media reported on the threat, but other sites had copied it by then.
The voice in the video clip, which lasted for three minutes and 42 seconds, said Singapore's cyber security defence network would be unable to stop the attack.
It said the "primary objective" of posting the video clip was to "protest the Internet licensing framework" imposed by the government.
While the hacker was speaking, a protest slogan was flashed on the screen saying: "I oppose censorship and support a free and open internet."
Under the new rules imposed on June 1, websites with at least 50,000 unique visitors from Singapore every month that publish at least one local news article per week over a period of two months must obtain an annual licence.
Websites granted a licence will have to remove "prohibited content" such as articles that undermine "racial or religious harmony" within 24 hours of being notified by Singapore's media regulator, the Media Development Authority has said.
The new rules have sparked anger in the city-state's robust blogging and social media community which has accused the government of a lack of consultation and raised fears the regulations are aimed at muzzling free expression.
Blogs and social media have gained popularity as alternative sources of news and opinion in Singapore, where mainstream newspapers are perceived to be pro-government.
In June, around 2,000 Singaporeans led by local bloggers attended a rally to protest against the rules.
Over 130 bloggers in the island-state also organised an Internet blackout in which they replaced their Facebook homepages with black screens featuring the words "#FreeMyInternet".
In the YouTube post on Thursday, the hacker urged Singaporeans to black out their Facebook profile pictures on November 5.
Singapore authorities have said the new rules provide clarity on existing standards for Internet content, and do not impinge on Internet freedom.
Explore further: Protesters rally in Singapore against new online rules