BEIJING — Chinese customs throughout the country investigated 604 criminal cases relating to drug smuggling in 2018 with 37.5 tons of various drugs and precursor chemicals seized, data from the top customs authority showed on June 25.

Of the 604 cases, 596 were drug smuggling crimes and a total of 4.61 tons of drugs were seized, including heroin, cocaine, methamphetamine and cannabis, according to the General Administration of Customs (GAC).

A total of 400 drug smuggling suspects were arrested and 70 drug smuggling and trafficking gangs were busted, showed the data.

In the first five months of 2019, nationwide customs investigated 284 drug smuggling cases and seized 567.35 kg of marijuana, heroin, codeine, methamphetamine and other drugs.

China will continue to maintain a tough stance against drug crimes, said a GAC official.