A court in southern China has sentenced four members of a Burmese drug smuggling gang to death for last year's kidnapping and murder of 13 Chinese sailors on the Mekong River.

China's official Xinhua news agency said Tuesday the gang leader, Naw Kham, and three of his associates were guilty of hijacking two Chinese cargo ships and killing the sailors in Thai territory in October 2011.

It said another gang member received a suspended death sentence and one was jailed for eight years at the hearing in Yunnan province's Kunming city.

The attack occurred in the so-called “Golden Triangle,” a region known for drug smuggling where the the borders of Laos, Burma and Thailand meet. It was one of the worst overseas attacks on Chinese nationals in recent history.

It prompted an angry response from China, which increased patrols in the area and summoned diplomatic officials from Thailand, Laos and Burma.

The drug smuggling gang was based in Burma's restive Shan state, which lies along the border with China.

State media says the men's trial finished in September after they pleaded guilty to intentional homicide, drug trafficking, kidnapping and hijacking. It said all six defendants plan to appeal the verdict.