They say they were forced from their homes in the hilly jungles of northern Laos by violent attacks and persecution by the Lao military. They crossed the border in search of a new life, only to find themselves languishing behind barbed wire at a camp in northern Thailand.

For more than a year, the displaced Hmong hill people at Huai Nam Khao camp have faced an uncertain future, passing their days under the watchful eyes of the Thai military. But two weeks ago, more than 800 were controversially repatriated, the biggest group to go back since returns from the camp began earlier this year.

The camp in Thailand's Petchabun Province houses some 78,000 Lao Hmongs in thatched huts. Most entered Thailand in 2005, according to the U.S. Committee for Refugees and Immigrants, a non-governmental organisation.

Thousands of the exiles had been living in forests around the town of Huai Nam Khao, relying on handouts from local villagers, before the Thai authorities forced them into makeshift settlements along both sides of the town's main road, MSF says. In mid-2007, they were moved to the barbed-wire confines of the new camp out of town.

The Thai military controls all access in and out.

During the Vietnam War, the U.S. Central Intelligence Agency recruited the Lao Hmong, a hill tribe minority who also live in Thailand and Vietnam, to fight alongside U.S. forces. When the Pathet Lao communist government took over in 1975, the exodus began. As many as 300,000 people including many Hmong fled to Thailand.

The more recent Hmong exiles at Huai Nam Khao camp say they were subject to attacks by Lao soldiers. Medecins Sans Frontieres, the only NGO working at the camp, says clinical interviews have shown several symptoms related to post-traumatic stress disorder as well as anxiety-related depressive disorders.

"They are traumatised by the past, and they believe the future is very similar to the past, maybe even worse than that," said Giles Isard, MSF's head of mission in Thailand.

Thai authorities said last month's repatriations were voluntary, but MSF called them forced returns.

The medicial charity has asked the Association of Southeast Asian Nations, the U.N. secretary-general and the governments of France, the United States and China to ensure Thailand and Laos resolve the issue according to international standards of refugee protection.

UNHCR, the U.N. refugee agency, said in a statement it was concerned about "lack of transparency and the absence of any third party to monitor the return operations".

MSF's Isard said the repatriation came after a mass protest by displaced Hmong from the camp against an agreement between the neighbouring governments to send the hill tribe people back to Laos.

Some 5,000 Hmong who participated in the protest outside the camp were rounded up, and around 400 people are still missing, Isard said.

"Families have been torn apart," he said. "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."

REFUGEES OR ECONOMIC MIGRANTS?

If MSF is right that repatriations were forced, this could mean a breach of the principle of non-refoulement, where under international humanitarian law no refugee or asylum-seeker should be forced to return to countries where they face persecution.

Thailand is not party to a 1951 global convention on the status of refugees, but the principle of non-refoulement still applies.

Another point of contention is the lack of transparency. Thai authorities have refused to give UNHCR access to the camp or let the agency monitor the screening process. MSF says the exclusion of a third party in the process was a condition demanded by the Lao government during negotiations with the Thai government.

Thailand, which has seen an influx of refugees from neighbouring countries in recent years - especially from Myanmar - sees the Hmong at the camp as illegal economic migrants and casts doubt on whether they were really fleeing from persecution.

"That is the point," Isard said. "An organisation like UNHCR can go in and assess the situation and determine (who is a refugee and who is not). Why is it that the Thai government does not want the UNHCR there?"

Exile groups in the United States - where almost 250,000 Lao refugees have settled since 1975, according to a 2000 UNHCR report - have regularly lobbied against planned repatriations.

Most recently, the plight of the Hmong was covered by Rebecca Sommer, a New York-based activist and founder of Earth Peoples, who in 2005 and 2006 interviewed refugees from the Huai Nam Khao camp for her film Hunted Like Animals.

But Isard says MSF did not receive any response to its latest request for international players to help resolve the Hmong issue. "Maybe they (the Hmong) are not a priority," he said. "We feel like we are approaching a subject that people do not want to discuss."

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