CHANGSHA - Police in the central province of Hunan have 24 drug production suspects in custody.

A total of 500 kg of finished ketamine, 125 kg of semi-finished drugs, 9 tonnes of materials and a large amount of cooking tools were seized in a recent raid, the police told the press on Wednesday.

Dingcheng District Police chief Hong Zhenkun said officers received a report on June 4 that some people were producing "washing powder" in an unoccupied house. The unpleasant smell emitting from the property had caught the attention of nearby residents.

The gang fled the scene the night before the raid, but the narcotics police captured a person who had helped them rent the workplace.

Six suspects were later detained in Guangdong Province in August with the support of local police. Another 17 people were captured in December.