US-based group the Fact Finding Commission (FFC) said Hmong had resisted being sent back for fear of persecution, a claim denied by the Lao government which said they were returned unrestrained, travelling in two buses.

Thai authorities at 0100 GMT Saturday "handed over 160 Hmong illegal migrants" at the Vientiane-Nong Khai border point, Lao foreign ministry spokesman Yong Chathalangsy told AFP, saying the hand-over was peaceful.

Many Hmong in the 1960s and 70s fought alongside US forces when the Vietnam War spilled into Laos. After the war ended in 1975, hundreds of thousands fled to Thailand and many were later resettled in the United States.

The former Hmong commander of a CIA-funded "secret army," General Vang Pao, now a 77-year-old US citizen, was arrested in California last week with eight others, accused of plotting a violent coup against the Lao government.

In northeastern Thailand over 7,000 Hmong, including both political and economic refugees, have for years lived in and around informal refugee camps, many of them hoping to eventually settle in the United States.

But Vientiane and the military rulers in Bangkok have agreed to repatriate those who are deemed illegal migrants and found to be Lao citizens, in a process not supervised by the UN refugee agency.

In January, Thailand failed to forcibly return some 153 Hmong with UN refugee status after they barricaded themselves in a detention centre and threatened suicide, but in May Thailand sent 31 Hmong back to Laos.

Agence France-Presse