Bangkok  - The French humanitarian aid group Medecins Sans Frontieres called Thursday on the governments of Thailand and Laos to halt forced repatriations of ethnic Hmong to communist Laos, where they face possible political persecution.

An estimated 800 ethnic Hmong refugees from the Huai Nam Khao camp in Thailand's Prachin Buri province were forcibly returned to Laos by the Thai government Sunday, and Thai authorities have threatened to repatriate another 6,700 soon.

The repatriations came after the Thai military rounded up about 5,000 refugees who had taken part in a protest march against an agreement between the Thai and Lao governments to send them back to Laos.

"Thai authorities claim that these were voluntary repatriations. It is hard to believe," said Gilles Isard, Medecins Sans Frontieres' head of mission in Thailand. "Families have been torn apart. One of our Hmong staff members who joined the protest has been sent back to Laos without her children, and we know of other similar cases. Many of these refugees have expressed grave fears at the prospect of being sent back to Laos."

The aid group has been providing medical assistance to Hmong refugees in Thailand for the past three years.

Hundreds of thousands of Hmong, an ethnic minority group that was used by the US military as a guerrilla force in their "secret war" against communism in Laos during the Vietnam War, have fled to Thailand since Laos went communist in 1975.

While many have been resettled in the United States, thousands of others have been rejected for resettlement or have chosen to stay in Thai camps rather than return to their homeland.

Thailand refuses to acknowledge the Hmong as refugees, classifying them as displaced persons or economic migrants instead.

It has been Thailand's policy to work with Laos in repatriating the Hmong remaining in Thailand to discourage further migrations.

The United Nations and humanitarian organizations such as Medecins Sans Frontieres (MSF) have opposed the policy on the grounds that the repatriations have been forced and there is no independent organizations monitoring the Lao government's treatment of the Hmong, a former enemy.

"MSF believes that the total lack of transparency surrounding the management of this crisis only exacerbates the problem," Isard said. "If the government of Thailand and Laos would accept an independent monitor, then this issue might be resolved." (dpa)