Chinese police have arrested 12,125 people during a crackdown on the sale of narcotics online and have confiscated more than 300 kg of illegal drugs, state news agency Xinhua reported on Sunday.

Police were tipped off to the scale of the problem after uncovering chatrooms in the two western cities of Lanzhou and Xian that were being used to peddle drugs, it said.

Newcomers were only allowed to enter the chat room after being introduced by 'acquaintances' and taking drugs live via webcam, Xinhua cited a police officer as saying.

Police began detaining suspects in early September, the report added. The youngest was 14, it said.

Criminal suspects turned to the Internet as it is harder for them to be detected that way, it said.

Websites must take responsibility in fighting such illegal activities and new laws be drafted to cope with this new problem, Xinhua added.