Clients wanting to stay overnight in sauna and massage parlors must now show ID and register their personal information, according to the city's security bureau's latest regulation.

"The regulation went into effect at 1 am yesterday morning," He Jing, deputy director of the security bureau of Guangzhou, capital of Guangdong province, said.

"It affects people going to sauna and massage venues from 1 am to 8 am only, and visitors to these venues at other times will not be affected" he added.

The point of the stipulation is to prevent criminal suspects from hiding out in such establishments, as well as inhibit sex trade, He said.

"Some of these health centers have become dens of iniquity in past years owing to an absence of efficient supervision and management," He said, adding "Sauna and massage venues are entitled to refuse admission to clients who refuse to register their ID ".

The security bureau will regularly dispatch investigators to ensure the new regulation is upheld.

Penalties imposed on those found to be in violation of the regulation range from warnings to revocation of business licenses.

Sauna and massage parlor proprietors say the new regulation affects business, and regular clients that it infringes on their privacy.

Chen Zhaomin, a Guangzhou resident who has hitherto been a regular overnight patron of sauna and massage venues, went home early yesterday morning rather than register his ID at a sauna house in the city's Tianhe district.

"I chose to leave because I think registering under my real name is an imposition," the 33-year-old told China Daily yesterday.

A sauna proprietor surnamed Dong said the regulation has negatively affected his business.

"On average, 100 clients stay overnight at our sauna center every day throughout the year. During peak periods, such as the biannual trade fair, as many as 300 clients stay overnight " he said.

"But last night when the regulation came in to force, only 60 people stayed."

Li Hongwei, a woman white- collar worker, however, said she thought the regulation would improve the management of the city's entertainment venues and crack down on the sex trade.

"Many entertainment venues in Guangzhou have recently become hotbeds of vice," she told China Daily.

Lin Lingfeng, a local lawyer, said the regulation standardizes operation of the city's entertainment venues.

"It has the same legal basis as showing proof of identity when checking into a hotel, opening a bank account or applying for a phone line," Lin said.