A photo splashed across the Internet showing an alleged prostitute, naked and being pulled by the hair by a policeman, has sparked criticism of excessive force.

The photo, along with several others and a video clip, was published online by local media covering a police raid on prostitution and gambling dens in the central Chinese city of Zhengzhou, Henan province.

A news website run by the China News Service last Thursday evening covered the overnight crackdown but the report drew little attention until noon on Monday.

Nonetheless, local police found themselves in the spotlight after the picture was widely circulated, prompting criticism from netizens on news portals and forums.

The picture depicts a bald plainclothes policeman grabbing the hair of a naked woman and forcefully pulling her head upwards. It set off huge blasts of criticism among Chinese netizens over his excessive use of force against the alleged prostitute.

One netizen with a nickname of "Zhonghuare'er" asked whether it was necessary for police to treat a suspected prostitute like a murderer. Another netizen nicknamed "Yitiandajian" questioned if it was legitimate to take photos of prostitutes and publish them.

Some netizens have even threatened to dig out the identity of the bald cop through so-called "human-flesh searching", or having someone acquainted with the person disclose his identity online.

"You cannot insult suspects' dignity because they break the law," said Wang Lei, a professor from the law school of Peking University. "Law enforcement units should protect suspects' privacy while allowing media reports."

The publicity department of the Bureau of Public Security of Zhengzhou has held a meeting on the issue, an officer surnamed Wang at the bureau said yesterday, though the outcome of the meeting was not immediately available.

Calls to the city's publicity department went unanswered.

An unnamed official from the police department in Henan said on Monday that the department had started to search the Internet for relevant photos after receiving interview requests on the issue, according to a report posted on a news website affiliated with China's Supreme People's Procuratorate.

Wu Changzheng, a professor from China University of Political Science and Law, said that the alleged prostitute should file an administrative lawsuit against the police for severe violations of her human rights and ask for an apology or damages.