GUANGZHOU - Police in a southern Chinese city known as a hotbed for production and trade of drugs have seized 4.8 tonnes of crystal meth, including 2.4 tonnes in liquid form, so far this year.

The narcotics control commission in Lufeng City, Guangdong Province, said on Wednesday that local police have uncovered 99 drugs cases, raided 24 drug production sites and caught 171 suspects this year.

On Wednesday, the commission launched a crackdown on drug smuggling by sea.

Already this year, local narcotics control staff found five shipbuilders and 11 ships helping or directly involved in drug smuggling by sea. They also arrested a fugitive suspect from an earlier case.

Since Lufeng emerged as a major meth production base in 2008, local authorities have embedded 28 work groups in three parts of the city most notorious for drugs.