Tran Anh Kim (R) was sentenced after a four-hour trial
A Vietnamese court has sentenced pro-democracy activist Tran Anh Kim to five-and-a-half years in prison for subversion against the communist state.
The former army officer was a member of the Democratic Party of Vietnam and the pro-democracy Bloc 8406, both of which are banned.
He was accused of publishing pro-democracy articles on the internet.
Four other activists are to be tried on similar charges in the latest round of dissident trials in Vietnam.
A number of other democracy activists have already been jailed this year in what some analysts say is a crackdown ahead of the next Communist Party Congress scheduled for early 2011.
The 60-year-old Kim was arrested in July on charges of conducting propaganda against the state.
He was later indicted with the more serious crime of "conducting activities to overthrow the people's administration" - charges that carry a maximum penalty of death.
"I joined the Democratic Party of Vietnam and Bloc 8406 to fight for democratic freedom and human rights for the Vietnamese nation through peaceful dialogue and non-violent means," he said.
Journalists were allowed to cover the four-hour trial at the court house in the northern town of Thai Binh.
Judge Tran Van Loan said Kim's activities had amounted to a "serious violation of national security". He said he had worked with "reactionary Vietnamese and hostile forces in exile".
The trial of four other pro-democracy activists - Le Cong Dinh, Nguyen Tien Trung, Tran Huynh Duy Thuc and Le Thang Long - on similar charges is to begin in Ho Chi Minh City on 20 January.