HOHHOT, Dec. 1 (Xinhua) -- Police in north China's Inner Mongolia Autonomous Region have arrested 13 people and seized 750 kg of caffeine in a recent drug ring crackdown.

The police in the city of Baotou received a tip-off about a drug-dealing group when probing a detained local drug user, and further investigations revealed that a woman surnamed Gao led a local drug dealing network involving several hierarchies.

Gao, whose husband and younger son are both serving jail terms after being convicted for drug-related offenses, was found transporting the caffeine in a truck with her elder son at a toll station in a recent raid.

The local police found the caffeine hidden in 30 bags in the truck and detained both suspects. In separate raids, the police tracked down the other suspects in Inner Mongolia and neighboring Shanxi Province.

Further investigations into the case are underway.