Vu Hung is one of several dissidents facing trial this week
A court in Vietnam has sentenced a man to three years in prison for hanging a banner over a bridge in Hanoi which called for multi-party democracy.
Vu Hung is one of a several pro-democracy activists who were arrested last year, accused of spreading propaganda against the state.
Rights groups say another activist, the poet Tran Duc Thach, has also been sentenced to three years in jail.
Seven others face trial in Hanoi and Haiphong city later this week.
'My little voice'
According to the prosecutor and the judge, former teacher Vu Hung hung a three-metre (10-foot) banner from a bridge in Hanoi last July.
The banner said corruption was "sucking the blood of the people", and inflation was "killing" them.
It also said the Communist Party should "immediately proceed with democratisation, pluralism and multi-party rule".
After a three-hour trial, judge Tran Van Vy said Hung's behaviour was a "danger to society".
"I just want to contribute my little voice to make society better," Hung told the court.
Poet Tran Duc Thach was one of nine people being tried this week for propaganda against the state under Penal Code Article 88, which rights activists say criminalises peaceful dissent.
Six other dissidents, including writer Nguyen Xuan Nghia, are to go on trial on Thursday in the port city of Haiphong, while another activist will be tried in Hanoi.
A diplomat with knowledge of the cases told Reuters news agency the dissidents were affiliated with Bloc 8406, a three-year-old group advocating democratic reform.
The Communist government allowed a brief period of enhanced openness in the run-up to Vietnam's accession to the World Trade Organization and hosting of the Apec summit in late 2006.
Analysts say it has since clamped back down on people with opposing views.