An official says a court in central Vietnam has sentenced three political activists to up to three and a half years in prison for distributing anti-government leaflets.

Presiding Judge Vi Van Chat said that the three were convicted of "spreading propaganda against the state" at Thursday's half-day trial in Nghe An province.

He says they were also ordered to serve up to 18 months under house arrest, adding that the fourth defendant was given a two-year suspended sentence.

Chat declined to give details.

Phil Robertson, deputy Asia director of Human Rights Watch, says in a statement that the four are Catholic activists who were arrested after passing out pro-democracy materials. He called for their immediate release.