Cambodian mortar fire reportedly injured a Thai soldier, putting a fragile 10-day-old ceasefire in jeopardy.

The mortar round was said to have struck Hill 469 in Ubon Ratchathani province today, wounding a Thai troop with shrapnel.

In a statement, Thailand's Second Army Area said: 'As a result of the incident, one soldier was injured. The injured soldier is Sergeant First Class Prachaya Philachai, Platoon Leader of the 1st Rifte Platoon, Infantry Company 6021 (RDF). He sustained shrapnel injuries to his right arm. Medical personnel assessed his condition as Green category (minor injuries) and not life-threatening.'

The soldier was evacuated from the field and taken to Nam Yuen Hospital, where he is in stable condition, the statement added.

Cambodia has allegedly dismissed the cross-border fire as an 'accident', claiming two of its soldiers were also injured in a 'rubbish heap explosion' in Cambodia's Preah Vihear province, opposite Ubon Ratchathani.

Thai Prime Minister Anutin Charnvirakul has demanded an explanation for the alleged peace breach.

He said: 'At the military-to-military level, we have been told the incident was an accident, but we are seeking clarification on how responsibility will be taken.'

The leader added that Thailand was 'acting within the agreed framework' but will respond to Cambodia 'if necessary'.

Thailand and Cambodia declared a ceasefire on December 27, ending weeks of conflict that left at least 26 Thai soldiers dead and one Thai civilian injured.

In Cambodia, the number of military fatalities is believed to be much higher, though regime chiefs have not revealed the actual figure.

At least 600,000 people have been displaced on both sides of the border.

Defence ministers from both nations signed the agreement at a border checkpoint. Among the conditions stipulated was the repatriation of 18 Cambodian soldiers being held by Thailand since July.

The second truce follows the collapse of an earlier flimsy peace pact brokered by US President Donald Trump in July, in a bid for a Nobel Peace Prize nomination.

Thai and Cambodian diplomats have travelled to China's Yunnan province for trilateral talks to 'consolidate' the ceasefire.