Thailand’s military government is to deport 100,000 refugees who have been living in camps along the border with Burma (Myanmar) for more than two decades, a move rights groups say would create chaos at a tense time for both countries.

The military overthrew the remnants of an elected government in May after months of sometimes violent street protests. Its National Council for Peace and Order has rolled out tough measures it says are needed to restore order and has promised a return to democracy next year.

“We are not at the stage where we will deport people because we must first verify the nationality of those in the camps,” a Thai army deputy spokesman, Veerachon Sukhontapatipak, said. “Once that is done we will find ways to send them back. There are around 100,000 people who have been living in the camps for many years without freedom. Thailand and Myanmar will help facilitate their smooth return.”

Last month, threats by the junta to arrest and deport undocumented migrant workers triggered the departure of more than 200,000 Cambodians, who are a key component of the fishing and construction sectors.

Thailand scrambled to reverse that exodus by opening service centres to help the migrants secure work permits. There are also an estimated 2 million Burmese migrant workers, the largest contingent of such labourers in the country. But without any legal status or marketable skills, the refugees have long been seen as a burden by the Thai state.

An estimated 120,000 Burmese refugees live in 10 camps along the Thailand-Burma border, according to the Border Consortium, which coordinates NGO activity in the camps.

An aid worker who has been helping the refugees said the Thai army appeared serious about the repatriation. “The authorities said this time they are going to be very strict. It seems like they’re really pushing for repatriation,” said the aid worker, who asked not to be identified. “The situation in the camps is very tense because people don’t know what’s going to happen.”

The refugees fear economic and logistical difficulties in returning as well as sporadic fighting in parts of northern Burma.

In his weekly televised speech on Friday, the junta leader, General Prayuth Chan-ocha, said Burma and Thailand would oversee the smooth repatriation of the refugees. “Thailand and Myanmar will facilitate the safe return to their homeland in accordance with human rights principles,” he said.

But rights groups say there is a lack of transparent and clearly defined policy to deal with refugees. “When Prayuth spoke on Friday he left out what the conditions for the return would be,” Sunai Phasuk of Human Rights Watch said. “The National Council for Peace and Order can only do this under the conditions expected by the international community.