The Chinese authorities secretly executed a man who took part in violent protests against a hydroelectric project in 2004, his lawyer said.
Chen Tao was among tens of thousands who demonstrated against the Pubugou dam in Sichuan province. Locals say the dam will displace 100,000 people.
The protests turned into a riot which left a policeman dead. Mr Chen was found guilty of killing the policeman.
Mr Chen's lawyer, Ran Tong, said he had not been allowed to attend his appeal.
Mr Ran said he heard about the execution when he went to the high court in Sichuan to ask about progress in the case.
"I am extremely angry about this because since the first trial (in April last year) I have repeatedly asked them for an appeal date and they have always told me that the case was being worked on," he told the French news agency AFP.
"The appeal was held in secret. They tricked us and secretly executed Chen Tao."
Three other people have been jailed, one for life, in connection with the case.
Thousands of paramilitary police were deployed in Sichuan's Hanyuan county to restore order after the riots.
Work on the dam was then suspended for several months but resumed in September last year, AFP said.
Popular unrest is one of the Chinese government's greatest fears. There has been an increase in incidents in recent years, driven by anger at official corruption, illegal land seizures and rising income disparities.
In one of the most serious incidents, police shot three villagers in Dongzhou, southern Guangdong province, during a land protest in December 2005.