Local residents spotted the elephant's body in a war-left bomb pit at the Keo Seima Wildlife Sanctuary in Keo Seima district on Saturday and reported it to the rangers.
Din Bunthoeun, acting director of the Mondulkiri Provincial Department of Environment, said the male elephant was thought to have wandered away from its herd and became trapped in the deep crater within one or two days before it died.
"According to examination, the dead elephant bore wounds on its front legs, and it was among a herd of 10 to 20 elephants that were sighted in the area in April," he said.
Khvay Atiya, a spokesperson for the Ministry of Environment, expressed deep sorrow over the death of the wild elephant, Xinhua news agency reported.
"This is a significant loss for our natural resources," he said.
Atiya called on stakeholders, particularly local residents, to increase their participation in protecting and preserving the elephants.
In January, a seven-month-old endangered Asian elephant was also found dead in Mondulkiri province, with a sharp force injury in its lower part of the chest.
Listed as endangered on the International Union for Conservation of Nature Red List, Asian elephants are some of the largest mammals on the planet.
According to the Ministry of Environment, it is estimated that there are currently 400-600 Asian elephants in Cambodia's natural forests, mainly in the Cardamom Mountains and eastern plains of Mondulkiri, Ratanakiri and Stung Treng provinces.