Prime Minister Hun Sen once again attacked ex-opposition leader Sam Rainsy for pledging “autonomy” to Montagnards, claiming – seemingly incorrectly – the ethnic minority does not exist in Cambodia.

“We respect all minorities such as Jarai, Steang, Phnong, but we have never had Montagnards,” the premier said to supporters in Australia on Friday.

The National Police filed a complaint accusing Rainsy of “treason” last week over a 2013 meeting in which he pledged autonomy to Montagnards should he be elected prime minister. He and Montagnard advocate Kok Ksor signed a document that mostly quoted the UN Declaration on the Rights of Indigenous Peoples. The Cambodian government is a signatory to the declaration.

“They offered autonomy to manage four provinces, and we should not forget that during the signing they used three flags – Cambodia, US and Degar,” Hun Sen said, referring to a term for Vietnamese Montagnards.

The premier claimed that using a flag to represent the ethnic minority group alongside national flags showed clear intent to elevate them to equal standing. “What does this mean? We will lose four provinces and those provinces will be attached to Degar,” he continued.

Read more: On his last night in Cambodia, a Montagnard’s tale calls into question notion of ‘voluntary’ repatriation

Rainsy has refuted the accusation, maintaining he never had any intention of granting independence or ceding land. The reference to “autonomy”, he has said, simply referred to the group’s freedom to pursue a traditional way of life.

Hun Sen also claimed Montagnards are an “ethnic minority of Vietnam”.

“It is not different from giving four provinces to Vietnam.”

In fact, the word “Montagnard” is a vague umbrella term meaning “people of the mountain”, and encompasses a variety of ethnic tribes that once lived in the mountains of Vietnam.

The Montagnard Assistance Project identifies Jarai as one of the “five major tribes” under the umbrella. Around 20,000 Jarai live in Cambodia. In recent years, hundreds of persecuted Montagnard refugees have also fled Vietnam into Cambodia, although the vast majority have been denied refugee status.

Rainsy pointed out in an email that 50 years ago, former King Norodom Sihanouk “actively helped the Montagnards . . . to preserve their cultural identity as well as their administrative rights . . . without jeopardizing Cambodia’s unity, independence, sovereignty, and territorial integrity”.

He also noted the term “Montagnard” includes other recognised minority groups in Cambodia, but accused Hun Sen of obfuscating facts “for political reasons”.