Three Burmese troops were killed yesterday after clashes with ethnic militias shortly after the first deployment of joint military patrols tasked with ensuring the safe passage of Chinese cargo ships along the Mekong River.

The Bangkok Post reported that the soldiers had been part of patrol comprised of Burmese and Lao personnel. The incident took place 20 kilometres north of the Golden Triangle intersection between Thailand, Burma and Laos, and is believed to have involved militia troops loyal to the ethnic Shan drug kingpin, Nor Kham.

He had been initially blamed for the killing of 13 Chinese sailors in October that prompted the deployment of river security, although police now believe it to have been the work of nine Thai soldiers. They have been detained, and are facing murder charges.

Following the massacre, nearly one million methamphetamine pills were found onboard the hijacked Chinese ships. The Mekong is a well-used passage for drug traffickers smuggling narcotics into Thailand, and police are investigating whether the Thai soldiers have links to drug rackets in the Golden Triangle.

The deaths yesterday again highlight the volatility of a waterway that cuts through territory controlled by armed militias, but which China needs to transport goods to Southeast Asian markets. Beijing has around 300 soldiers stationed along the river, and sent 11 of its own patrol boats to guard the nine vessels sailing from Guanlei port in Yunnan to Thailand’s Chiang Rai over the weekend.

Thailand is also included the four-country patrols, but the chief of its army, Gen Prayuth Chan-ocha, warned last week of possible territorial disputes arising from the initiative. Thailand would join the mission “carefully”, the Bangkok Post reported him as saying, and Thai ships would need to be in charge of any patrol entering Thai territory.