Three suspects were transported to the southwestern Chinese city of Kunming on Tuesday and two more were being moved Wednesday, China's Public Security Ministry said.
Police wouldn't say what nationality the suspects were. They were caught in Laos on March 19, 2013, along with more than half a ton of methamphetamine produced in the lawless "Golden Triangle" region encompassing parts of Laos, Myanmar and Thailand.
China stepped-up law enforcement cooperation with its southern neighbors in the wake of the killing of 13 Chinese crew members in an attack on their ships on the upper reaches of the Mekong River in October 2011.
In that case, six suspects were extradited to China from Laos and Myanmar, four of whom were executed in March 2013. After temporarily suspending shipping on the river, China signed an agreement with Thailand, Myanmar and Laos to conduct joint patrols on the river, which originates in the mountains of western China before flowing through the Golden Triangle and out to the South China Sea.