Seven people were hospitalized in Shanghai on Tuesday after a suspected gas leak in their apartment, which houses 33 tenants.

None of the tenants' lives are in danger, but the accident rings an alarm bell on the safety of group-renting, the practice of dividing apartments into smaller rooms and renting them separately to earn more money.

At about 1 am on Tuesday, some of the 33 tenants felt uncomfortable in the apartment in the Tainxiang residential building, and called police for help.

A preliminary check by the property management office showed the waste pipe of the water heater fell off, leaking waste gas into the three-bedroom apartment, according property management office employee.

The employee, who asked not to be named, said the apartment is about 170 square meters.

The Shanghai-based Xinmin Evening Post reported that there are at least two apartments that accommodate dozens of people in the building, which is located on the city's Jiangning road in the Jing'an district. The apartments are reported to be rented by a trade company.

"We are aware of the shared renting in the apartment but we can do nothing to stop it. The landlord insisted on leasing the house in this way," said the officer.

Overcrowded apartments are rampant in big cities like Beijing and Shanghai, as new graduates and migrant workers can't typically afford the skyrocketing housing prices or the rental fees.

The average monthly rent for a three-bedroom apartment in the Tianxiang residential building is about 7,500 yuan ($1,200), according to anjuke.com, an online property agent.

According to the National Bureau of Statistics, housing prices in most of the country's cities have continued to rise in recent months. Shanghai led the first-tier cities of Beijing, Guangzhou and Shenzhen in January's housing price growth with a 20.9 percent year-on-year rise.

In August 2007, the city issued a regulation on house-leasing targeting group co-habitants. It set the average living space in rented houses at 5 square meters per person, designated separate rooms as the minimum leasing unit and prohibited the division and renting out of sitting rooms.

Beijing also announced strict rules curbing group renting last July. The rules specified that each room in an apartment should accommodate only two tenants with a minimum living space of at least 5 sq m per person, while the kitchen, bathroom, balcony and basement cannot be leased for living purposes.

Shanghai Mayor Yang Xiong vowed to tackle recurring group renting at a news conference in January. He said authorities in different departments and districts should coordinate to ensure the regulations are followed.

Hu Shoujun, a sociology professor at Fudan University in Shanghai, said that government regulation of group renting is needed as it creates risks such as fire hazards, personal safety and noise for neighbors.

"But ultimately the government and real estate developers should consider the housing needs of low-income groups, especially migrant workers," he said.

wuni@chinadaily.com.cn