HANOI (REUTERS) - A court in Vietnam has upheld prison sentences against 15 people it said are guilty of plotting to bomb the country's largest airport in Ho Chi Minh City last April, state media reported on Tuesday (June 5).

Dang Hoang Thien, the leader of the group, was charged with"terrorism against the people's administration" in December last year and given a 16-year prison sentence.

His associates were given 18 months' probation to 14 years in prison.

The group "planted fuel bombs in the carpark and at the arrival hall at Tan Son Nhat International Airport" in April last year, the Ministry of Public Security said in January.

The Ho Chi Minh City People's High Court upheld the sentences because Thien and others failed to provide sufficient evidence proving their innocence, the Thanh Nien newspaper reported.

It said the group had received money from the California-based Provisional Government of Vietnam, led by US citizens Lisa Pham and Dao Minh Quan, to purchase weapons, make petrol bombs, carry out terrorism activities and incite riots and protests against the administration.

In January, Vietnam said it had listed the Provisional Government of Vietnam as a terrorist organisation because it established groups inside the country to "execute acts of terrorism and sabotage, and assassinate officials".

The group is loyal to the now-defunct state of the Republic of Vietnam, which was once backed by the United States and ruled the southern half of the country until the Vietnam War ended in 1975.

A spokesman at the US Embassy in Hanoi said in January that the organisation is not designated as a terrorist group by the US State Department.