There are currently at least five journalists and 19 bloggers being held on various charges in Vietnam, according to the international watchdog Reporters Without Borders.
Tuoi Tre newspaper said its reporter Hoang Khuong was convicted of giving a police officer a bribe of $710 in June last year in order to get an impounded motorbike returned.
Khuong paid the bribe as part of reporting on police corruption and later wrote two articles about it that appeared in Tuoi Tre, triggering public anger at the police.
Khuong has been quoted as telling police he was doing his job as a journalist and received no personal gain as a result of bribing the officer.
Judges at the two-day trial in southern Ho Chi Minh city sentenced him to four years in jail, and the officer who took the money to five, according to a report in Tuoi Tre.
Representatives of Tuoi Tre were not permitted to give evidence at the trial. The paper's editors declined comment.
Editors and journalists in Vietnam do not have to submit everything they print or broadcast to state censors, but are well aware of which topics they are to avoid.
In 2008, a journalist for Thanh Nien newspaper was sentenced to two years in prison for his coverage of a high-profile corruption case at the transport ministry.