This is the tense moment rival soldiers discussed who allegedly fired the first shot as gunfire broke out along the Thai-Cambodia border.

Footage shows the troops calmly debating on Monday, after artillery was reportedly fired into Chong Bok area of Ubon Ratchathani in eastern Thailand.

A Thai soldier said: ‘We want to confirm the facts, from our perspective, regarding what happened yesterday and the day before. The Thai side would like to confirm that we do not know which side the shot was fired from, but the sound of the explosion occurred on the Thai side.'

A Cambodian soldier replied: ‘Regarding the explosion, I don't know which side it came from. But for my side, it is certain that there are no explosions or shooting from the Cambodian side to the Thai side. However, I did hear gunfire yesterday and it was only from the Thai side.'

Both men denied starting the clash while their colleagues filmed the exchange.

Just a day earlier, Thai Army spokesman Major General Winthai Suvaree said artillery and gunfire were allegedly detected from Cambodian positions near the border.

Explosions and gunshots were reportedly heard in intervals, from 12 noon to 1:30 pm local time, targeting Hills 600 and 527.

Thai forces claimed they only returned fire when their positions came under attack. The situation settled at 1:30 pm, with no further gunfire exchanges.

The army spokesman said: 'It was not a natural border skirmish but a planned provocation intended to produce footage and reports accusing Thailand of breaking the truce.'

Thailand and Cambodia have been fighting for more than a century over several undemarcated sections of their 817-kilometre (508-mile) border, which was originally mapped by France in 1907 while Cambodia was still its protectorate.

But tensions flared in the long-disputed frontier as both accused each other of instigating violence on July 24, which killed at least 48 and temporarily displaced some 300,000 on both sides of the border.

Cambodia claimed responsibility for the alleged war crime of firing rockets into Thailand that struck a gas station, killing a number of children.

The two nations have reached a shaky truce following talks facilitated by Malaysian Prime Minister Anwar Ibrahim, chair of the Association of Southeast Asian Nations (ASEAN).