BEIJING (Reuters) - China on Tuesday warned Western countries against taking up the case of a prominent dissident, Liu Xiaobo, who is facing trial for subversion, after the United States and European Union called for his release.

A portrait of one of China's best known dissidents Liu Xiaobo is seen in front of the China liaison office in Hong Kong August 23, 2009. REUTERS/Tyrone Siu

Liu’s lawyer said last week that Chinese prosecutors had decided to try him on charges of “inciting subversion of state power” for publishing essays critical of the ruling Communist Party and helping organize a petition demanding democratic transformation.

Liu has been among his country’s best known critics of restrictions on citizens’ rights, and was detained late last year while helping oversee the launch of the “Charter 08” petition for political change.

The European Union urged China on Monday to release him unconditionally, while the United States pressed Beijing to respect the rights of all Chinese citizens who peacefully express their desire for “internationally recognized freedoms.

But Chinese Foreign Ministry spokeswoman Jiang Yu said such calls amounted to interfering in the country’s judiciary.

“These accusations are unacceptable. China is a country of rule of law. The fundamental rights of Chinese citizens are guaranteed by the law,” she told a regular news conference.

“I want to stress that Chinese judicial bodies handle cases independently. Outsiders have no right to interfere. We oppose any external forces using this case to meddle in China’s internal affairs or judicial sovereignty.”

Jiang’s comments underscored that her government is unlikely to heed international pressure growing Liu, who could face trial as soon as next week. Chinese courts come under Communist Party control and rarely reject prosecution accusations, especially in politically sensitive cases.

If convicted, the 53-year-old dissident could be sentenced to up to 15 years in prison.

A former literature professor, Liu has been a thorn in the party’s side since 1989 when he joined a hunger strike supporting student protesters days before the army crushed the pro-democracy movement centered on Tiananmen Square that year.

Liu’s wife, Liu Xia, told Reuters on Tuesday that he had met with his lawyer on Monday and been told to prepare to stand trial “very soon.”