Thai troops have repatriated more than 4,000 ethnic Hmong to Laos amid criticism from the US and other nations that the returnees could face persecution by the government there.
The repatriation process all but ended the Hmong's three-decade search for asylum following their alliance with the US during the Vietnam War.
The US and rights groups have said the Hmong could be in danger if returned to the country that they fought, unsuccessfully, to keep from falling into communist hands in the 1970s.
The European Union said it was "deeply dismayed" by the forcible deportation and issued a statement that urged Laos to ensure the Hmongs' human rights are protected and international observers are granted "unfettered access" to them.