The 91st Mekong River joint patrol led by China, Laos, Myanmar and Thailand concluded Friday as two Chinese law enforcement boats returned to Guanlei Port in the southwestern province of Yunnan.

A total of 111 law enforcement officers from the four countries participated in the mission in five vessels and covered 605 km in four days, according to the provincial public security department.

Joint visits, inspections and an anti-drug publicity campaign were launched in key waters, with a Burmese merchant ship rescued, 19 vehicles, 35 people and 21.7 tonnes of cargo inspected during the mission.

Affected by the coronavirus epidemic, law enforcement authorities of the four countries jointly directed the operation with a remote video command system for the first time. The law enforcement also sent a publicity team to promote knowledge about the epidemic prevention and control.

One of the Chinese law enforcement boats involved in the patrol will continue to conduct a one-week combat drill in Laos.

The joint patrol program started in December 2011 after a gang hijacked two cargo ships and killed 13 Chinese sailors in Thai waters on Oct. 5 that year.

The Mekong River, known as the Lancang River in China, is a vital waterway for cross-border shipping among China, Laos, Myanmar, Thailand, Cambodia and Vietnam.