The United States on Tuesday said it was "deeply concerned" over a sweeping new Internet law in Vietnam which bans bloggers and social media users from sharing news stories online.
The decree, seen as a further crackdown on online freedom in the authoritarian country, says sites such as Facebook and Twitter should only be used "to provide and exchange personal information".
"We are deeply concerned by the decree's provisions that appear to limit the types of information individuals can share via personal social media accounts and on websites," the US Embassy in Hanoi said in a statement.
Decree 72, signed by Prime Minister Nguyen Tan Dung and made public last Wednesday, stipulates that Internet users should not use social networks to share or exchange information on current events.
It is not clear how the law will be implemented or the penalties faced, but commentators said it could in theory make it illegal to share links to stories or even discuss articles published online in Vietnam's state-run press.
"Fundamental freedoms apply online just as they do offline," the US statement said, adding it could cramp the growth of the communist nation's "budding IT sector" by deterring innovation and foreign investment.
The decree, which comes into force in September, also bans Internet service providers from "providing information that is against Vietnam, undermining national security, social order and national unity".
The decree has been widely condemned by watchdogs including the Committee to Protect Journalists and Reporters Without Borders.
Vietnam's official Nhan Dan newspaper on Tuesday dismissed criticism of the decree as "defamation and distortion".
In Vietnam, some people have "turned personal blogs and Facebook into places to disseminate incorrect views, attack the party and state and organise opposition," it said.
Vietnam, branded an "enemy of the Internet" by Reporters Without Borders, bans private media and all newspapers and television channels are state-run.
Many citizens prefer to use social media and blogs to get their information rather than the official press.
But the authoritarian government has repeatedly attempted to stifle growing online debate.
So far this year 46 activists have been convicted of anti-state activity and sentenced to often lengthy jail terms under what rights groups say are vaguely defined articles of the penal code.
At least three bloggers were also taken into custody in June alone, all accused of anti-state activity.
Explore further: Vietnam to clamp down on social media news postings