By Rachel Harvey
BBC News, Bangkok
Thai officials said no violence was used to move the Hmong from the camp
More than 4,000 ethnic Hmong have arrived in Laos after being forcibly repatriated from Thailand, despite international protests.
The BBC has learned that among those deported is a group of 158 Hmong officially recognised as refugees by the UN, which has expressed its dismay.
The Hmong say they face persecution in Laos because they backed US forces during the Vietnam war.
But the Thai government regards the Hmong as illegal economic migrants.
The Thai authorities said the operation to deport the Hmong had been completed on Monday night.
Within 24 hours, more than 4,000 people were removed from the camp in northern Phetchabun province, where they had been living for the past five years. The UN refugee agency, the UNHCR, had not been allowed to visit them beforehand.
A second group of 158 Hmong, who had been held in a detention centre in the town of Nong Khai for three years and were officially recognised as refugees by the UNHCR, were also forcibly repatriated.
The UNHCR expressed dismay, saying Thailand's actions had set a grave example.
A spokeswoman for the organisation in Bangkok told the BBC offers had been made by third countries to resettle those granted refugee status, but that Thailand had consistently rejected the idea.
"Discussions were ongoing and had not reached a conclusion," Ariane Rannery said. "But now they've been deported and have now been forced to return to a place they had fled from."
She added: "The UNHCR, although it has no formal presence in Laos, hopes to get access to the returned Hmong."
Thailand says it has been given assurances by the government in Laos that returnees will not be mistreated.