In a letter responding to opposition lawmakers, Foreign Affairs Minister Hor Namhong explained that Vietnamese authorities had used herbicides on Cambodian-planted crops last month because the plots encroached on 16 hectares of Vietnamese territory.

The letter, sent to National Assembly President Heng Samrin and dated May 4, was a direct reply to 12 Cambodia National Rescue Party (CNRP) lawmakers who had asked the National Assembly to take action after Vietnamese authorities reportedly used “poisonous chemicals” on corn, cassava and rice crops in Tbong Khmum province last month.

However, according to Namhong’s letter, the crops had been planted on Vietnamese land mistakenly believed to be in the border province.

“Our people planted crops on about 16.6 hectares of Vietnam’s land,” Namhong’s letter reads. “This caused Vietnam to react by spraying poisonous chemicals on our people’s crops.”

Mao Monyvann, the CNRP lawmaker in Kampong Cham who first called attention to the herbicide incident, expressed his disdain for the revelation, adding that it was a blow to Cambodia’s sovereignty.

“I will pour all my efforts into studying [the map used] and talk with legal advisers in order to confront this case, since this affects Cambodian people and our sovereignty,” he said.

Puth Phat, a resident of Cherng village, which is affected by the spraying, said that he had been cultivating the land since 1985, but was chased out after the area was made an undemarcated “buffer zone”.

“This year, we kept cultivating . . . so they just used poisonous chemicals to kill the crops,” he said.