Some online advertisements for housekeeping services, specifically services for vacant dwellings, have appeared in Beijing since the local government announced its plan to investigate vacant dwellings in the city.

Vacant dwellings are defined as dwellings that have been sold but are unoccupied, according to the National Bureau of Statistics of China.

Yu Xiuqin, spokeswoman for the bureau, said that, as one of the pilot cities for the research into vacant dwellings, Beijing will select no more than 10 communities in the city to investigate.

The communities will be located both downtown and in remote areas, but because such a limited number of communities are to be investigated, the results will not be used to calculate vacant dwellings across the city.

Research by the Beijing Union University between 2004 and 2006 on vacant dwellings estimated that the ratio in Beijing was 27 percent in 2007.

"It is difficult to count vacant dwellings, even in developed countries, because it involves citizens' private property," Yu said.

Government departments should cooperate in carrying out the survey, Yu said, but emphasized that it is only a trial. The survey will include door-to-door interviews, water, gas and electricity meter checks and interviews with property management companies.

Although the investigation is still to start, some people have already built their businesses on it.

On a website in Beijing, three advertisements, all of which were updated after Sunday, promote housekeeping services for vacant dwelling owners.

"I think I am doing a good thing for the majority. I only help people manage their real estate," said a man, surnamed Jin, who offers such a service.

Jin said he cleans vacant property twice a month and protects the house from water or electricity leaks.

He added that real estate speculators are his target market, but he admitted that he has had only two clients since he launched the service two months ago.

"I am still confident about the business since people have a need for such a service," Jin said.

The cost of the service depends on the size and date of the property and ranges from several hundred to thousands of yuan a month.

Jin said he does not think the government will be able to determine the exact number of vacant dwellings in the city, because of the difficulty in entering people's property.

"As a man without any real estate in Beijing, I support investigating vacant dwellings, but the situation is so complicated," Jin said.