Many Vietnamese use blogs as a way to find out the latest news
Vietnam has tightened restrictions on internet blogs, banning bloggers from raising subjects the government deems inappropriate.
Blogs should follow Vietnamese law, and be written in "clean and wholesome" language, according to a government document seen by local media.
Internet service providers will be held accountable for the content of blogs they host.
More than 20 million Vietnamese use the internet - a quarter of the population.
Source of news
Vietnam's burgeoning blogging community has become an important source of news for many people in the country, where the national media is still tightly controlled by the state.
The new rules, drawn up by the Ministry of Information and Communications, require internet service providers to report to the government every six months and provide information about bloggers on request.
The rules ban posts that undermine national security, incite violence or disclose state secrets.
It is unclear whether the new regulations will apply to international companies such as Google or Yahoo; currently the most popular blogging host in Vietnam is Yahoo!360.