One Cambodian soldier was killed in a brief exchange of gunfire between Thai and Cambodian soldiers on Wednesday morning in a disputed border area in Ubon Ratchathani, the defence ministry in Phnom Penh said.

“The Thai army first opened fire on a trench that had been a Cambodian army base for a long time, resulting in the loss of one of our soldiers,” the ministry said in a statement.

Thailand said its soldiers were trying to negotiate with Cambodian troops to back away from taking up a position in a disputed area but came under fire.

“Cambodian forces misunderstood the situation and started using weapons, so Thai forces retaliated,” an army spokesman said, adding that there were no Thai casualties. The exchange lasted about 10 minutes.

The incident occurred near Chong Bok in Nam Yuen district of Ubon Ratchathani about 5.30am.

According to Matichon Online, the Cambodian soldiers were digging a trench in the disputed area. It published a photo of what it said was the trench. There were no soldiers in the photo.

The 2nd Army said Thai soldiers on routine patrol saw Cambodian soldiers “changing the geographic aspect of the disputed area” and asked them to stop what they were doing.

The Cambodians responded with gunfire, sparking the brief clash, it said.