The Information Center for Human Rights and Democracy said Liu Xianbin, 41, was taken away by police Monday for allegedly ''inciting subversion to state power,'' a charge commonly used against dissidents.

The Hong Kong-based watchdog said Liu was official arrested Wednesday after having published articles in support of other dissidents, including Tan Zuoren and Huang Qi who were both given prison sentences earlier this year after publicly blaming shoddy construction of buildings for the deaths of thousands of schoolchildren in the May 2008 earthquake in Sichuan.

It said Liu's arrest came after Beijing sought to tighten control over ''local and foreign hostile forces'' ahead of the July 5 anniversary of deadly ethnic rioting in Urumqi, the capital of northwestern China's Xinjiang Uygur Autonomous Region.

Liu was in 1991 sentenced to two and a half years in prison on counter-revolutionary charges after the Tiananmen protest ended in a bloody crackdown. He was subsequently imprisoned in 1999 on subversion charges after he helped organize the Chinese Democratic Party.

He was released in 2008 and became a co-signatory of Charter 08, a political reform blueprint drafted by academics and rights advocates calling for government reform, according to mainland media reports.

''The arrest could well mean Liu's third time in prison,'' another Tiananmen protest student leader Wang Dan said on his Facebook account Wednesday.

''What Liu has done is done for the progress of China. He shouldn't be facing harsh treatment. We strongly urge for public pressure to help free Liu,'' he said.

==Kyodo