Worries arose over the quality of the buildings put up as part of China's social housing program for the poor after substandard walls were found in a project for shantytown dwellers in Baotou city, the Inner Mongolia Autonomous Region.

The project, in the Binhe district and developed by the Shenhua Group Corp Ltd (Shenhua Group), was specially constructed for shantytown dwellers in Shiguai district, a main coalfield area in the city.

The 1,200,000-square-meter project contains 226 buildings, which can accommodate 39,000 people, as well as a school and a hospital, according to the company's website.

Work on the project lasted for two years and finished in 2010. More than 5,000 families have since moved in.

Doubts began to form over the quality of the buildings when 451 families living there complained that the surface of their walls had cracked and peeled off in places, Xinhua News Agency reported on Saturday.

"The walls easily peel when I touch them and small pieces of plaster from the walls break up very easily," Huang Shaoting, a local resident who moved in in September, told Xinhua.

"I spent all my savings and borrowed another 70,000 yuan ($10,756) from my relatives and my child for the apartment. I planned to live a happy life in the new house, and I never thought I would be faced with troubles arising from poor construction right after I had moved in.

"(The wall peels off) partly because of the use of too much mortar, an additive which helps cement become sticky, so it can easily be daubed on the wall," an insider in the building industry, who requested anonymity, told China Daily on Sunday.

Mortar is often used because it is cheap, he added.