Thailand closed northeastern border crossings with Cambodia and said Wednesday it was withdrawing its ambassador and expelling the Cambodian ambassador to protest a land mine blast in which a Thai soldier lost a leg.

Cambodia responded Thursday that it was downgrading diplomatic relations with Thailand to their lowest level and recalling all Cambodian staff from its embassy in Bangkok.

Relations between the Southeast Asian neighbors have deteriorated sharply since May when a Cambodian soldier was killed in an armed confrontation in one of several small patches of land both countries claim as their own territory.