YINCHUAN, May 29  -- Northwest China's Ningxia Hui Autonomous Region on Thursday relaxed its family planning policy to allow couples to have a second child if either parent is an only child, the local legislature said.

A Resolution on the Amendment to the Population and Family Planning Regulations was passed at a meeting of the Standing Committee of the Ningxia Hui Autonomous Region People's Congress on Thursday.

The resolution said the new regulation will be applied starting Thursday. The policy will be implemented by the regional government.

Ningxia's family planning policy already allows people from ethnic minority groups to have a second baby. The relaxation of the birth policy mainly affects the Han population in urban areas.

The results of a survey conducted by the regional government showed that about 47.4 percent of Han families eligible to have a second child as a result of the policy change are willing to have another baby.

China's family planning policy, put in place in the late 1970s, is designed to curb population growth.

In addition to Ningxia, the municipalities of Beijing, Tianjin, Shanghai and Chongqing as well as the provinces of Zhejiang, Jiangxi, Anhui, Sichuan, Guangdong and Jiangsu have also changed their policies.