BEIJING - Ahead of the 20th anniversary of the bloody crackdown on Tiananmen Square this week, Chinese authorities have rounded up dissidents and shipped them out of town. Now, they've even shut down Twitter.
Along with their usual methods of muzzling dissent, the authorities extended their efforts Tuesday to silence social networking sites that might foster discussion of any commemoration of the events of June 3-4, 1989.
The action is a new sign of the government's concern of the potential of such technology in an authoritarian society where information is tightly controlled.
"There has been a really intensified clampdown on quasi-public discussion of awareness of this event," said Xiao Qiang, adjunct professor of the Graduate School of Journalism at the University of California-Berkeley, and director of The Berkeley China Internet Project.
"It's a discussion about where China is now and where China can go from here. So the authorities are making a major crackdown to block user-generated sites such as Twitter and show there is no right to public discussion," he said.
China has the world's largest online population, and Internet communities have proven increasingly influential in spreading word of events to everything from student protests to group shopping excursions.
People are going outside the normal, controlled channels to set up communities online, spreading information about campus unrest and other activities that the government considers to be potentially subversive.
Government Internet monitors have shut down message boards on more than 6,000 websites affiliated with colleges and universities, apparently to head off any talk about the 1989 events, according to the Hong Kong-based Information Center for Human Rights and Democracy.
Numerous blogs maintained by edgy government critics such as avant-garde artist Ai Weiwei have been blocked and the text-messaging service Twitter and photo sharing site Flickr could not be accessed within China on Tuesday. Video sharing site YouTube has been blocked within China since March.
"We understand the Chinese government is blocking access to Flickr and other international sites, though the government has not issued any explanation," said Jason Khoury, spokesman for Yahoo, which owns Flickr. "We believe a broad restriction without a legal basis is inconsistent with the right to freedom of expression."
Officials from Twitter did not responded to a request for comment.
Authorities have been steadily tightening surveillance over China's dissident community ahead of this year's anniversary, with some leading writers already under house arrest for months.