Thai officials said no violence was used to move the Hmong from the camp
Thailand has removed about 4,000 ethnic Hmong from a northern refugee camp to deport them back to communist-ruled Laos, despite international criticism.
No violence was used as all of the Hmong were moved out of the camp in Phetchabun province, officials said.
Thailand describes them as economic migrants. The Hmong say they face persecution in Laos because they backed US forces during the Vietnam war.
The United Nations urged Thailand to stop the deportations.
Col Thana Charuvat, who is co-ordinating the repatriation, said about 5,000 soldiers, officials and civilian volunteers had entered the camp in Huay Nam Khao village late on Monday morning.
By late afternoon, the last of the Hmong had been driven from the camp in army trucks to buses that were waiting to take them to the border with Laos.
"There was no resistance from the repatriated Hmong because we used psychological tactics to talk with them, to assure them that they will have a better life in Laos as the Lao government has confirmed," Col Thana said.
No journalists were allowed into the camp during the operation, which went ahead despite calls from the UN, the US and several European nations to halt the deportations.
"We also urge the Lao People's Democratic Republic to treat humanely any Lao Hmong who are involuntarily returned, to provide access for international monitors, and facilitate resettlement opportunities for any eligible returnee," said the US State Department spokesman Ian Kelly.
He noted that both the Office of the United Nations High Commissioner for Refugees and the Royal Thai Government have deemed many of the Hmong in need of protection because of the threats they might face in Laos.
Thai government spokesman Panithan Wattanayakorn told the BBC that officials had concerns for about 100 of those being deported.
But Thailand had been assured that those people would be pardoned on their return to Laos, he added.
Hundreds of thousands of Hmong fled Laos after the communist Pathet Movement took power in 1975.
Many have settled in the United States, Australia and other countries, but a sizeable population remains in Laos and complains of persecution from the authorities.
Some Hmong have been fighting a low-level insurgency against the government since 1975.