Relations between the US and Vietnam are warming

The Vietnamese authorities have neither confirmed nor denied the authenticity of the documents.

US President Bill Clinton is due to visit Vietnam later this week, the first visit by a US president since the end of the Vietnam war.

'Exploitation'

The documents display considerable concern about the spread of religion in Vietnam and accuse foreign elements of fostering religious organisations.

One document quoted by the Far-Eastern Economic Review says the imperialist enemies and their gangs consider using the exploitation of religion as a very important factor in resisting the revolutionary movement.

A statement issued by the foreign ministry just said that Vietnam's attitude to religion had been clarified many times and that the suggestion that religious groups have been suppressed in the country were slanderous distortions.

In September, the US State Department published a report accusing the Vietnamese authorities of only allowing officially-recognised religious organisations to function.

The report said that the authorities harassed and arbitrarily detained some believers, such as Buddhists and Protestants.

It is not yet clear what President Clinton will say on the issue during his visit, but US officials have raised the possibility of the president attending a church service in Vietnam.