The deal, brokered by US President Donald Trump in October, was meant to wind down a conflict that peaked with five days of clashes in July that killed at least 43 people and displaced about 300,000 civilians on both sides.

Both sides agreed under the pact to withdraw heavy weapons from the border region and to give access to ceasefire monitors. Thailand also pledged to return 18 captured Cambodian troops.

Cambodia said the situation on the border "remains calm". However, Thailand's response suggested that tensions have returned with the suspension of the pact's implementation.

"The truth has become clear that hostilities still remain," Royal Thai Army (RTA) chief Pana Klaewblaudtuk said in a statement.

"The Thai Army needs to suspend the joint declaration to safeguard our right to self-defense," it said, referring to the pact.

Thailand has often accused Cambodia of laying new landmines along their border in breach of the Ottawa Convention banning anti-personnel mines.

The RTA said four soldiers were wounded by Monday's landmine blast in Sisaket province.

Apparent mine blasts wounding Thai troops were a key catalyst when tensions flared in July, igniting a long-standing territorial dispute over a smattering of century-old border temples.

Cambodia's defense ministry said on Tuesday it "expresses its regret" over the latest mine blast but that the munitions were relics of past conflicts.

"After the incident, both military forces on the front lines had communicated with each other and as of now the situation remains calm," it said in a statement.

The ministry said Cambodia "remains committed" to the peace deal, signed in Kuala Lumpur on October 26 under the stewardship of Trump and Malaysian Prime Minister Anwar Ibrahim as chair of the ASEAN regional bloc. 

However, Thailand's Prime Minister Anutin Charnvirakul has confirmed he will delay the release of the captured Cambodian troops, a key plank of the peace plan.

Anutin chaired a National Security Council meeting in Bangkok on Tuesday morning and was due to travel to Sisaket later to meet the wounded soldiers.

Foreign Minister Sihasak Phuangketkeow told reporters the suspension of the deal's implementation would be reported to the United States and Malaysia.

"It is also important that Cambodia take responsibility by showing regret, participating in the investigation and ensuring this does not happen again," Sihasak said.

The Thai-Cambodia truce has generally held since July 29.

However, analysts have said a comprehensive peace pact adjudicating the territorial dispute at the core of the conflict remains elusive.

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