BANGKOK (AP) — A study says a Chinese-backed plan for Cambodia to build the Mekong River's biggest dam would destroy fisheries that feed millions and worsen tensions with Vietnam, the downstream country with most to lose from dams on the waterway.

The three-year study, posted on the website of the U.S.-based organization that Cambodia's government commissioned it from, says the Sambor dam will "generate large power benefits to Cambodia, but at the probable cost of the destruction of the Mekong fishery, and the certain enmity of Vietnam."

It says the dam designed by China Southern Power Grid Co. with a 620-square-kilometer (239-square-mile) reservoir would dwarf the biggest dam currently being built on the Mekong.

The experts recommend the government defer the project while looking for better alternatives.