Premier Li Keqiang (third from right) poses with Thai Prime Minister Prayut Chanocha (third from left), Cambodian Prime Minister Hun Sen (second from right), Laotian Prime Minister Thongsing Thammavong (second from left), Myanmar Vice President Sai Mauk Kham (right) and Vietnamese Deputy Prime Minister Pham Binh Minh (left) at a welcoming ceremony on Tuesday before the Lancang-Mekong Cooperation Leaders' Meeting, scheduled for Wednesday, in Sanya, Hainan province. WU ZHIYI / CHINA DAILY

Security along the Lancang-Mekong River has improved greatly since China, Laos, Myanmar and Thailand established a law enforcement cooperation mechanism to combat rampant cross-border crime.

Before this, the number of cross-border crimes on the river - including drug-trafficking, terror attacks, smuggling of firearms and humans, and illegal immigration-had risen sharply, according to the Ministry of Public Security.

"Such crimes tend to become severe and complex on the river, posing a serious threat to regional security and stability," said a senior official at the ministry, who declined to be named.

In October 2011, the four countries agreed in Beijing to set up a law enforcement cooperation mechanism, under which they conduct joint patrols to combat cross-border crimes along the river.

The decision was taken after 13 Chinese sailors were killed by a drug trafficking ring in the Golden Triangle area of the river, comprising parts of Thailand, Laos and Myanmar.

"The law enforcement mechanism has played an essential role in maintaining safety and promoting economic prosperity," the official said.

According to the Ministry of Public Security, between December 2011 and last year, the four countries conducted 41 joint law enforcement activities on the river. These greatly reduced cross-border crime.