Chinese dissident Zhao Shiying has been detained by authorities in the southern Chinese city of Shenzhen. Rights activists say the arrest is probably a sign that a crackdown against signatories of Charter 08 is continuing.

Charter 08 is a petition drafted in late 2008 calling for political and democratic reforms in China. It was signed by hundreds of intellectuals and dissidents, including Mr Zhao.

Officers raided the home of Mr Zhao - who uses the pen name Zhao Dagong - on Monday, confiscating two computers, books and notes. His wife and two sons were taken to the local police station for questioning before being released.

Separately, Chinese lawyers and US rights activists have demanded that the whereabouts of prominent human rights lawyer, Gao Zhisheng, be made known. Mr Gao, who has been in police detention for almost a year, has reportedly gone missing since September according to his brother, raising fears for his fate.

Mr Gao had been a constant thorn in the side of the Beijing authorities. He defended oppressed miners and drafted open letters to senior Chinese leaders demanding an end to the persecution of Christians and members of the spiritual Falun Gong community.

Photo Chinese policeman by gbastistini (flickr)