Four members of a gang accused of masterminding the murder of 13 Chinese sailors on the Mekong River last year were sentenced to death at a court in southwest China on Tuesday.

The sailors were killed last October in a raid on two Chinese cargo boats on the Mekong, an attack thought to have been carried out by a notorious gang in the "Golden Triangle", an area known for drug production and smuggling.

The reading of the verdicts was shown live on state television.

The trial finished in September after the gang of six men pleaded guilty to intentional homicide, drug trafficking, kidnapping and hijacking, state news agency Xinhua said in September.

Another defendant received a suspended death sentence, while a sixth man was handed eight years in prison at the sentencing at Kunming Intermediate People's Court.

The gang, based in Myanmar's northern Shan state, was led by Myanmar national Naw Kham, who was one of the men sentenced to death.

At least one of the remaining five gang members is Thai, but the nationalities of the other four is unclear.

The "Golden Triangle" is where the Mekong River runs through China, Myanmar, Thailand and Laos.

Last year's incident sparked an angry reaction from China, which summoned diplomatic envoys from Thailand, Laos and Myanmar and asked authorities to speed up investigations into the incident.