HANOI (AFP) – Vietnam has jailed for up to nine years three labour activists found guilty of disrupting security, after a trial that lasted less than a day, a court official said.

Nguyen Hoang Quoc Hung was given the heaviest sentence of nine years while two others, Doan Huy Chuong and Do Thi Minh Hanh, were each sentenced to seven years in jail, said an official of Tra Vinh people's court in the southern Mekong Delta.

The maximum penalty for the charge of disrupting security is 15 years in prison.

The official, who declined to be named, did not give further details about Tuesday's trial.

US-based Human Rights Watch said the trio, all in their 20s, were arrested in February for distributing anti-government leaflets and helping workers to organise strikes for better pay.

Nguoi Lao Dong (Labourers) newspaper said they instigated several strikes in Ho Chi Minh City and Dong Nai province between last December and February. They were also charged with distributing "reactionary" leaflets in the two areas, the paper added.

Human Rights Watch said Chuong was first arrested in October 2006 after helping to found the United Workers-Farmers Organisation (UWFO), which Vietnam has banned. State media said he was later sentenced to 18 months in jail for "spreading distorted information to undermine the state".

Communist Vietnam bans independent labour organisations, while trade unions are under strict government control.