Prominent writers and scholars in China have called for the release of a dissident who co-authored a petition to the government calling for democratic freedom.
About 50 intellectuals have signed a petition for Liu Xiaobo's release that is being circulated on the Internet.
Liu was formally arrested this week after being detained at a secret location for more than six months. The authorities accused him of inciting subversion against the state.
The 53-year-old writer was one of the chief architects of the so-called "Charter 08," a petition calling for political and legal reforms and respect for human rights in China. The document was signed by more than 150 human rights activists, writers and lawyers.
The United States called on Beijing Thursday to release Liu and to respect the right of Chinese people to peacefully express their desire for freedoms.
Liu was detained a day before "Charter 08" was released on December 10, International Human Rights Day.
Human rights groups say more than 30 signatories have been questioned by police or put under house arrest since the petition was published on the Internet.