PHNOM PENH -- The Cambodian Mine Action Center (CMAC) experts have recovered more than 2,000 pieces of war-era unexploded ordnance (UXO) buried on a school campus in northeastern Kratie province, a mine clearance chief said on Monday.

"Within a three-day period of operations on Aug 11-13 at the Queen Kosamak High School in Kratie province, CMAC's Remnants of War team has cleared 2,116 pieces of unexploded ordinances as the remnants of war," CMAC's director-general Heng Ratana told Xinhua.

Those unearthed UXO included 2,033 M79 grenades, 63 DK75 rounds, 18 Fuze M48 shells, one H107 bullet and one B40 bullet, he said.

"According to our experts at the site, there still be many more pieces of unexploded munitions within this area," Ratana said, adding that the school will be closed temporarily for a few more days for a clearance operation.

He said the explosive munitions were discovered after the school cleared land to expand a garden.

Cambodia is one of the countries worst affected by landmines and explosive remnants of war (ERWs). An estimated 4 million to 6 million landmines and other munitions had been left over from three decades of internal conflicts and a US bombing campaign.

According to Yale University, between 1965 and 1973, the United States had dropped some 230,516 bombs on 113,716 sites in Cambodia.

Cambodian Prime Minister Samdech Techo Hun Sen wrote in his book titled, "Hun Sen: 10 Years of Cambodia's Journey, 1979-1989," that the US bombings on Cambodia caused "tens of thousands of civilian casualties because of this vicious undeclared war."

According to the government's latest report, from 1979 to June 2023, landmine and ERW explosions had claimed 19,821 lives and either injured or amputated 45,205 others in Cambodia.