Police in Southwest China's Yunnan Province seized 23.3 tons of illegal narcotics in 2015, the provincial public security department said Sunday.

Police in the border province cracked down on 22,000 drug cases, and local rehab centers took in over 67,000 drug users in 2015, according to the department.

Last year marked the end of the province's five-year campaign against drug crime.

Yunnan is among the Chinese regions most affected by drug use, due to its proximity to the opium-growing Golden Triangle in neighboring Southeast Asian countries. It is also a source of domestic drugs.

Official data released in June 2015 showed that the amount of heroin and methamphetamine seized by Yunnan police accounts for around 80 percent and 70 percent of the country's total respectively.