Chinese police cracked more than 2,600 drug cases and arrested more than 2,900 suspects during a two-month multinational drug control operation in the southern border region.
The Second Safe Mekong Joint Operation ran from Jan 12 to March 12 with the assistance of Thailand, Myanmar and Laos.
The number of cases increased by nearly 70 percent and the number of suspects arrested rose 35 percent since the first operation in early 2013, according to An Guojun, deputy secretary-general of the China National Narcotics Control Commission.
As many as 3.75 metric tons of drugs were seized, including 170 kg of opium, 1.48 tons of heroin, 2.04 tons of methamphetamine pills and 48.9 kg of morphine.
In China, the operation was conducted across 16 provinces with a focus on Yunnan province and the Guangxi Zhuang autonomous region.
Chinese police set up checkpoints in the border area, strengthened inspections at docks and increased patrols along the Chinese section of the Mekong River.
"A number of armed forces, as well as criminal organizations from different countries have controlled the river basin to conduct drug-related crimes," An said.
He added that more than 100,000 drug-related cases were cracked on the Chinese mainland last year, and the major drug source for those illegal activities was the Golden Triangle.
Initiated by China in 2013, the Safe Mekong Operation normally lasts for two months and aims to enhance cooperation among the four countries to suppress illegal drug activities.
"China has been cooperating with the other three partner countries through international laws and mechanisms for longer than three decades, but our work has become much more efficient since the Safe Mekong Joint Operation," An said.
Permpong Chaovalit, secretary-general of the Narcotic Control Board in Thailand, said he appreciates that China initiated the operation two years ago, since "no single country can deal with this problematic issue alone".