The Thai army says it suspects English-speaking foreigners might be controlling Cambodian bomber drones that have targeted Thai forces during the ongoing border clashes.

The 2nd Army Area, which is responsible for northeastern Thailand, said on its Facebook page on Thursday morning that it doubted Cambodian soldiers were controlling the drones.

It said the word “finished” was heard during a radio communication when bomber drone attacks took place.

In addition, it noted that just when suicide drone attacks stopped, motorcyclists were seen leaving nearby hills. Such sightings happened in the Chong An Ma area of Ubon Ratchathani province.

Rumours that foreigners, possibly Russians, were helping with the Cambodian war effort circulated on social media earlier this year. They appear to have been prompted by a photograph showing two tall men in military fatigues with a group of Cambodian soldiers.

Gen Nattaphon Narkphanit, the deputy defence minister at the time, said an initial investigation showed the pair were Cambodian non-commissioned officers.

He also said at the time that the army had found no evidence of Russian-language communication during Cambodian military operations but investigations were ongoing.

The bomber drones used by Cambodia are first-person view drones and are controlled via optical fibre links, the 2nd Army Area said.

The army also said suicide drones — those intentionally crashed into targets — have been used to strike Thai bunkers sheltering soldiers.