Soldiers from Thailand and Cambodia exchanged artillery fire on Friday on a disputed stretch of their border near an ancient temple, which is claimed by both countries.
Thai officials say there was sporadic shelling.
The BBC reports it was the most serious incident on the border for some time. Tension has risen in the area in recent days, with both sides moving in extra troops and accusing each other of encroachment.
The Cambodian government has called it an "invasion" while the Thai military said it was a misunderstanding.
The incident ended after about two hours, with both sides confirming a ceasefire.
A Thai soldier was shot dead in the incident and four others were wounded.
The Cambodian government said a complaint would be sent to the UN Security Council.
