'Houses with limited property rights - investment for the future." Over the past couple of weeks, such advertisements in big, black fonts have hit Beijing. And the prices of such houses have been rising almost everyday. In eastern Tongzhou district, for example, the prices of some houses have risen by hundreds of thousands of yuan overnight. The craze stopped only when the Ministry of Land and Resources and the Ministry of Housing and Urban-Rural Development issued an emergency notice.

What are houses with limited property rights and why have they suddenly become so popular? The answer lies in China's dual land-use system: urban land is owned by the State and rural land by collectives, and they are meant for different uses. While houses built on urban land with permits are saleable, it is illegal to build houses on agricultural land. Besides, houses built on rural land earmarked for construction can only be sold to local residents.

But the rapid urbanization of China, with fast-expanding cities and skyrocketing realty prices, has also seen apartment buildings being built and sold in rural areas. Since such buildings are built without official permission, professional designs and quality control, the sale and purchase of the apartments in them are illegal. Worse, people who buy them cannot get any ownership certificate from the State. That's the reason they are called "houses with limited property rights".