Law enforcement agents from the Chinese mainland and Taiwan confiscated 1.36 tonnes of methamphetamine in a joint raid in March this year, the Ministry of Public Security's Narcotics Control Bureau said on Tuesday.

This is the largest bust in China in some 18 months.

Twelve suspects were apprehended, and two inflatable boats and two vehicles used for trafficking were seized, the bureau said.

It said mainland and Taiwan agents had followed leads uncovered in a previous joint maritime anti-drug operation in 2013, which led to a trafficking ring that had planned to transport drugs over land to Shishi City, Fujian Province, southeastern China.

The drug ring, led by Gong, one of the suspects, had planned to smuggle the narcotics overseas, the bureau said.

The raid lasted from the evening of March 17 to the morning of March 18, simultaneously on- and offshore.

Drug use has ballooned in China in recent decades, with estimates that the real number of drug users is somewhere around 14 million.

According to the Office for the China National Narcotics Control Commission, the number of registered drug users in China stood at 2.96 million at the end of 2014, 75 percent of of which were aged under 35.

The office said an online anti-drug campaign would be launched this month.