Vietnam blogger Nguyen Lan Thang airs news of detention on Facebook

A pro-democracy blogger broke the news of his own detention in Vietnam through Facebook, another sign of how the social network is shaking up the country’s activist movement and worrying its authoritarian rulers.

In a video message posted by activists soon after his detention at the Hanoi airport on Wednesday night, Nguyen Lan Thang said, “When you see this video it’s certain that I have been arrested by security forces.”

Security authorities, who rarely speak to the media, were not available for comment on Thursday.

Fellow activists who travelled to the airport to greet Thang said he was picked up there on his return from an overseas trip. Nonviolent activists are sometimes detained for a day or two and released, but can also be charged with national security offences and given long prison terms in a legal system controlled by the ruling Communist party.

Activist La Viet Dung said Thang’s family and friends were at the airport on Thursday seeking to get information about him. He said they were told by immigration officials that Thang was “working with security agencies” and there was no word on whether he would be released.

Thang recorded the message shortly before he flew home and told friends to spread it if he is detained.

Around one-third of Vietnam’s 90 million are online. Blogs, Facebook pages and YouTube have emerged as the main avenues for activists to spread news, commentary, video and photos, giving Vietnamese people accessed to uncensored information.