One soldier lost a leg and two others sustained minor injuries in the blast on Wednesday in Si Sa Ket province, which borders Cambodia, the Thai army said in a statement.

The soldiers were surveying the border area when the landmine exploded and were rushed to hospital for treatment, according to the army.

The explosion comes after weeks of relative calm following a Dec 27 ceasefire, reached after renewed clashes along the two countries’ 800km frontier. Fighting in July and again in December killed dozens and forced hundreds of thousands of residents to flee their homes.

The latest incident could complicate efforts to stabilise one of Southeast Asia’s most volatile border disputes. Both sides have repeatedly accused each other of violating truce terms.