A Thailand-based weekly journal, the Irrawaddy, has described the online assault, which blocks access for users in Myanmar, as persistent and very sophisticated.

In a posting on a temporary site hosted on a back-up server, it said the crackdown coincided with the anniversary of Buddhist monk protests against the junta that began in Yangon on September 18 last year.

Similar outages were reported at the Burmese-language New Era Journal and the Democratic Voice of Burma, an Oslo-based news outlet that aired footage of the 2007 protests and the ensuing crackdown.