Check on returned Vietnamese, govt told

The federal government has been urged to use a human rights dialogue to check on the welfare of asylum seekers it returned to Vietnam.

Senior officials from Australia and Vietnam will meet in Canberra for annual talks next week.

Human Rights Watch says the Australian contingent should ask about the whereabouts of two groups of recently-returned asylum seekers and demand the release of any in custody.

"Australia should publicly call on the Vietnamese government to immediately explain under what charges any of the returnees have been detained and release any detained arbitrarily," Human Rights Watch said in a submission to the Department of Foreign Affairs and Trade.

Australian border authorities have confirmed 46 asylum seekers were returned to Vietnam in April.

It's also believed asylum seekers on another boat which approached Western Australia's north coast in July have been returned to Vietnam and upon arrival three were detained by authorities.

Australia does not keep track of asylum seekers sent back and relies solely on the trust of Vietnam's assurances that it won't punish people.

The submission also raises concerns about the plight of at least 135 political prisoners, police brutality and the religious persecution of ethic Montagnard Christians in Vietnam's central highlands.

"Persecution continues unabated," Human Rights Watch said.

Hundreds of Montagnards have fled to Cambodia and other parts of southeast Asia in the past year.