Another 120 police dogs will be sent to customs offices across the country in the next two to three years to help bust drug-related crimes.

Dogs are playing an indispensable role in fighting drug smuggling, said Guan Xiangying, an official with the Anti-Smuggling Bureau of the General Administration of Customs.

They have helped police with nearly 500 cases since 2010 involving 1.5 metric tons of drugs, including heroin, methamphetamine, cocaine, ketamine and tons of phenylacetone, a chemical used to produce drugs.