Trade between Vietnam and the US is still low

Some congressmen have raised religious freedom in Vietnam as an issue to consider regarding passage of the agreement, which Hanoi is seeking to help meet growth targets.

Exiled Vietnamese religious leaders have also been urging the US to delay implementing a trade pact pending improvements in Vietnam's human rights record.

But, on Tuesday, Vietnam's communist authorities dismissed the impact of Mr Thich's case on the historic pact.

Crackdown

Mr Do is deputy head of the outlawed Unified Buddhist Church of Vietnam.

The head of the UBVC, Thich Huyen Quang, is also under house arrest in a remote part of Vietnam.

Vietnamese authorities have cracked down on dissent recently

On Thursday, Mr Do was to lead a convoy of church supporters to bring Mr Quang to Ho Chi Minh City for medical treatment.

The latest action by the authorities comes amid a widespread crackdown against religious groups and ethnic minorities, who staged large protests in February.

Among the issues that sparked the protests was the government's repression of fringe Protestant churches, which have attracted many followers from ethnic minorities in recent years.

The BBC Hanoi correspondent says Vietnam currently recognises six religious groups, but organisations which lack official acceptance face sustained harassment.