The 107th joint Mekong River patrol by China, Laos, Myanmar, and Thailand, concluded on Friday, with three Chinese law-enforcement vessels returning home to a port in southwest China's Yunnan Province.
A total of four vessels from China and Laos navigated over 600 km over four days and three nights, according to the Yunnan provincial public security department. Laos, Myanmar, and Thailand sent police to carry out land patrols.
The patrol had targeted illegal immigration in the Mekong River basin, said the department.
During the operation, the law enforcement officers have constantly warned passing merchant ships of heavy rainfalls and risks of rising water level.
The Mekong River, known as the Lancang River in China, is a vital waterway for cross-border shipping.
China, Laos, Myanmar and Thailand have been carrying out joint patrols on the Mekong River since December 2011.