SHENZHEN - Police authorities in the southern Chinese metropolis of Shenzhen have seized 10.4 tonnes of drugs during the past year.

During the past 12 months, local police uncovered nearly 2,600 drug cases and detained more than 3,300 drug dealers, the Shenzhen municipal bureau of public security said Tuesday.

Meanwhile, police reported 10,600 drug-takers in the city that borders Hong Kong.

Deng Guangsheng, head of the narcotics control department under the Shenzhen municipal bureau of public security, said police had intensified the fight against drugs since June last year.

Police also raided four drug production factories and there was a 70-percent drop in the number of drug cases uncovered in other cities but originating from Shenzhen.

Local narcotics control authorities also offered 3.35 million yuan ($511,300) in rewards for tip-offs leading to the uncovering of 447 drug cases.

Tuesday was International Day Against Drug Abuse and Illicit Trafficking.