Singapore's feisty online community reacted angrily Wednesday to an announcement that news websites including one operated by Yahoo! will have to obtain licences subjecting them to rules governing traditional media.

"It is obvious that the new rules are to set and control the tone of discourse online, a concern which the government has had for a while now," said Andrew Loh, the editor of socio-political website Publichouse.sg.

"The rise of social media, as an increasing number of Singaporeans get their news online, has now prompted the government to let go of its promised 'light touch' on the Internet," he wrote on the site.

Singapore is one of Asia's wealthiest and most wired nations but also one of the most regimented.

Its traditional media are widely seen to be pro-government, giving rise to alternative sources of news online amid growing discontent with the ruling party and its policies.

The popular news site of Yahoo! Singapore was included Tuesday on a list of 10 websites that will have to obtain annual licences starting Saturday -- all the nine others are sites run by mainstream Singapore media groups.

The Media Development Authority (MDA), the official media watchdog, said websites that have at least 50,000 unique visitors from Singapore every month and publish at least one local news article a week fall under the new rules.

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 the MDA.

International media watchdog Reporters Sans Frontieres ranked Singapore 149th globally in press freedom this year, down 14 places from 2012 and below neighbours such as Malaysia and Indonesia.

Yahoo! Singapore, which has a team of reporters doing independent coverage, has become a magnet for anti-government comments posted by readers in reaction to local news stories.

Executives at Yahoo! Singapore told AFP they would not comment until they see details of the licensing rules.

"It certainly looks like there's political motivation behind this new licensing framework, and the motivation seems to be to rein in Yahoo! Singapore," wrote prominent blogger Ravi Philemon.

Others questioned what they called the arbitrary nature of the MDA's decision to require Yahoo! to obtain a licence under the new regulatory regime while leaving untouched volunteer-run blogs also popular among Singaporeans.

"MDA's failure to explain how its new policy is to be applied at present suggest that the manner in which it is being introduced is opaque and arbitrary," wrote the editors of socio-political website The Online Citizen.

There was no immediate reaction from the MDA to the criticism.

In its announcement Tuesday, it said it expected "no change in content standards" since websites already must comply with content restrictions, citing in particular the need to curb "content that underlines racial or religious harmony" in the multi-ethnic society.

Traditional media outlets, owned by Singapore Press Holdings and state-linked broadcasting group Mediacorp, are subject to licences that can be revoked at any time by the authorities.

The People's Action Party, in power for more than 50 years, suffered its worst ever electoral performance in May 2011, getting an all-time low of 60 percent of the popular vote after the opposition and its supporters relied heavily on social media for campaigning.