Updated

Sok An, a deputy prime minister of Cambodia who was one of Prime Minister Hun Sen's closest political and personal allies, has died at age 66.

A government statement said he died of illness Wednesday at a hospital in Beijing. He had been absent from public life for several months and was widely understood to be undergoing medical treatment.

In 1980, Sok An became a personal secretary to Hun Sen when he was foreign minister in a government installed by Vietnam, which ousted the Khmer Rouge from power in 1979. He was best known internationally for negotiating with the United Nations to hold a tribunal to try leaders of the Khmer Rouge for genocide and other crimes. One of his sons is married to one of Hun Sen's daughters.