BANGKOK — Three Thai soldiers were wounded Saturday when one stepped on a land mine while on patrol near the Cambodian border, the Thai army said, in the latest flare-up of tensions despite a recent ceasefire agreement.

The explosion occurred in Sisaket province and “clearly demonstrates... that the use of concealed weapons in border areas continues to exist,” the army said, accusing Cambodia of violating the Ottawa Convention, which bans the use of anti-personnel mines.

Both Thailand and Cambodia are signatories to the treaty.

The Thai Foreign Ministry said the blast was the third such incident in less than a month and “confirmed” findings that new mines were being planted in violation of international law.

Saturday’s explosion came just two days after the two neighbors reaffirmed a ceasefire following five days of armed clashes last month that killed dozens on both sides and displaced more than 260,000 people.

That fighting erupted a day after five Thai soldiers were wounded by a land mine in disputed territory.

Maj. Gen. Winthai Suvaree, a Thai army spokesperson, called Saturday’s blast “a significant obstacle” to implementing the ceasefire and resolving disputes peacefully.

Cambodia’s Mine Action and Victim Assistance Authority rejected the allegations, insisting no new mines have been laid and highlighting its internationally recognized record of clearing over 1 million mines and nearly 3 million other unexploded munitions from past conflicts. Cambodia suggested earlier explosions may have been caused by remnants of decades-old fighting.

Tensions between the countries have been simmering since May, when a Cambodian soldier was shot dead by Thai troops in another contested border area, triggering cross-border boycotts and restrictions.

In Saturday’s incident, a Thai sergeant major lost his left foot, while two privates sustained minor injuries, the army said. — Agencies