A total of 22 policemen in Dongguan, the south China city notorious for its illegal sex trade, have been punished in a crackdown on prostitution, local police said on Tuesday.

Among them, nine policemen are in criminal detention and 13 others have received disciplinary punishments for dereliction of duty, bending the law for personal gain and harboring the sex trade, according to a statement from the provincial public security department.

Another 14 policemen are being investigated for their involvement in the sex trade, according to the statement.

Dongguan, seated in the Pearl River Delta in Guangdong Province, is famous for its lavish casino resorts, bath centers, and massage parlors, as well as its back-street brothels.

Police have been cracking down on the sex trade in the city for more than a month following a China Central Television report in early February on rampant prostitution there.

Yan Xiaokang, vice mayor of Dongguan and head of the city's public security bureau, was removed from his posts for dereliction of duty in mid February.

A statement from the Guangdong provincial committee of the Communist Party of China said that Yan's failures led to the persistent illegal sex trade in Dongguan, which has reflected very badly on the city, both domestically and internationally.