BEIJING  In an unequivocal rebuke to those pursuing political reforms, a Chinese court on Friday sentenced one of the country’s best-known dissidents to 11 years in prison for subversion.

Liu Xiaobo, 53, a former literature professor and a dogged critic of China’s single-party political system, was detained in December 2008 after he helped draft a petition known as Charter 08 that demanded the right to free speech, open elections and the rule of law.

The 11-page verdict, largely a restatement of his indictment, was read out Friday morning at the Beijing No. 1 Intermediate People’s Court, said Mr. Liu’s lawyer, Shang Baojun. In addition to his prison term, Mr. Liu will be deprived of his political rights for an additional two years, a penalty that will prevent him from writing or speaking out on a wide range of issues.

“We are just extremely disappointed,” said Mr. Shang, who added that Mr. Liu intended to appeal the verdict.