HANOI, Vietnam (AP) -- A pro-democracy blogger broke the news of his own detention and eventual release 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 Wednesday night, Nguyen Lan Thang said, "When you see this video, it's certain that I have been arrested by security forces."
On Thursday afternoon, Thang said he been released, also via Facebook.
"Too much taxpayer's money has been spent on me since yesterday," he wrote in reference to his detention. "My apologies to all of you."
Security authorities, who rarely speak to the media, were not available for comment.
Activists who traveled to the airport to greet Thang said he was picked up there on his return from a three-month overseas trip where he met with human rights groups and representatives of international organizations, including the United Nations.
Nonviolent activists are sometimes detained for a day or two and released, but can also be charged with national security offenses and given long prison terms in a legal system controlled by the ruling Communist party.
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 people are online. Blogs, Facebook and YouTube have emerged as the main avenues for activists to spread news, commentary, video and photos, giving Vietnamese access to uncensored information.
Facebook has emerged as the dominant social media network despite earlier efforts by authorities to block the site.
Some estimates say it has up to 70 percent penetration rate of the total Internet population.
The government has sought to control online expression, but is unable to implement a secure firewall like in neighboring China. According to Human Rights Watch, at least 61 activists have been convicted and sentenced to prison in Vietnam this year for nonviolent dissent, many of them via the Internet -- a significant increase over around 40 such convictions in 2012.
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