KUNMING - China, Laos, Myanmar and Thailand on Sunday began a new joint patrol on the Mekong River in the Golden Triangle Region as trade and transportation returns to normal after an attack last year in which 13 Chinese sailors were killed on the river.

The fleet of four patrol ships set sail at 7:30 a.m. from Guanlei Port, which is located in Xishuangbanna Dai Autonomous Prefecture in southwest China's Yunnan Province.

The five-day police patrol, the seventh since last December, will include a two-day inspection of the Laos-managed sections of the river, said Wang Bing, an officer in the Yunnan Provincial Border Control Corps.

The two-day patrol will send police to check ships, passengers and goods for drugs, weapons and stowaways travelling on the river, according to Wang.

"The joint patrols have been hailed by countries in the region for ensuring transportation safety and deterring criminals on the Mekong River," the official said, adding, "Thanks to the patrols, navigation on the river has returned to the level before last year's deadly attack."

The four-country joint patrol started in October 2011 to tackle safety concerns raised after a gang hijacked two cargo ships and killed 13 Chinese sailors on board in the waters of Thailand on October 5, 2011.

Statistics showed only 10 Chinese ships were navigating the river when the first such patrol was launched. That number had increased to 59 when the fifth patrol was conducted in August.