Paris-based Medecins Sans Frontieres (MSF), or Doctors Without Borders, said on Wednesday it no longer felt it could operate in the camp where it fed 4,700 Hmong.

Many Hmong, a hill people, fought alongside the US during the Vietnam War and Laos' communist government continues to hunt them down. MSF said refugees who fled to Thailand recounted killings, gang-rape and malnutrition inflicted by Laotian forces.

The Lao Veterans of America, which represents Hmong and other Laotians who supported the United States, went to the US Congress seeking aid for the refugees at the Huai Nam Khao camp in Thailand.

Both the veterans and MSF charged that the Thai military was trying to intimidate the refugees in hopes they would leave the four-year-old border camp.

Philip Smith, executive director of the Center for Public Policy Analysis, which promotes Hmong rights, called on Congress to act or for President Barack Obama to tap emergency funds to help the refugees.

The Nobel Prize-winning humanitarian group said it was leaving the camp after unsuccessfully appealing to the US, France and the UN to try to improve the refugees' plight.

MSF said Thailand and Laos wanted to close the camp by year-end. It estimated more than 1,500 Hmong have already been forced back to Laos since December 2005 and said there were credible reports that some were tortured. It also complained that outside groups including the UN High Commissioner for Refugees were denied access to the camp.

Four US senators earlier this year wrote a letter to Secretary of State Hillary Clinton urging her to look into the camp and to press Laos, with which the United States restored normal trade relations in 2004.

The senators said Thailand should not deport Hmong who have fears of persecution and called for a transparent screening process that meets international standards. -- AFP