BEIJING - A PHOTO showing a plainclothes policeman pulling a naked woman by the hair during a prostitution bust in central China has caused outrage on the Internet, where it has been widely circulated.

The photo was one of a series taken by local media covering a police raid on prostitution and gambling dens in Zhengzhou, capital of Henan province, said the official China Daily, which also published the controversial picture.

'Police in the mainland grab a person's hair in the process of law enforcement, and forcefully take naked photos by violent means,' one online user said Wednesday on popular web portal Chinaren. 'This is a criminal offence - much more serious than prostitution!'

A video clip of the raid, also widely available online, shows the plainclothes policeman bash down a door in what appears to be an upscale massage parlour.

'How many have you had tonight?' the policeman says to a naked woman sitting down on the floor - an alleged prostitute - as a client, also naked, crouches near her. The hair-pulling incident only appears in the still photo, not the video.

A spokeswoman at the Zhengzhou police bureau, who refused to be named, told AFP an investigation into the case was ongoing, but refused to provide any further details. -- AFP