Places in China for children to play safe and happy are shrinking, according to a national survey.

About 53 percent of the 2,500 primary and middle school students responding the survey said their homes were their constant play sites, while 45 percent of the respondents said they often played around residential areas or in parks, showed the survey, recently conducted by the China Youth and Children Research Center.

The respondents, who come from six main cities including Beijing, Shanghai, Guangzhou, Changchun, Chengdu and Lanzhou, also chose schools and classmate homes as their main play sites.

Nineteen percent students surveyed said they seldom did sports because "there are no appropriate sports sites", it showed.

"Children often play at home because they have few other choices," said one of the survey organizers Wang Xiaobo, associate researcher with the Tianjin Academy of Social Sciences, noting there are fewer places in Chinese cities for children to play around.

Wang said, with China's scarce land resources, more and more outdoor sports places in cities have been occupied for urban development, and the soaring number of private cars in the country prompted urban communities to allocate more space for parking, which makes children play sites continue dwindling.

"Many Chinese parents don't like their children to play outside out of worries about worsening road traffic and public security," said Wang, adding the lack of sports has seriously affected children's health.

Another survey by the Ministry of Education (MOE) shows that while Chinese students have got taller in recent years, there is an overall decline in their physical strength.

It found that, in 2005, Chinese students jumped an average of three centimeters less in the long jump compared with 2000.

The ministry urged schools throughout the country to improve their sports facilities so students could build up their body strength.

"Courts, gymnasiums and fields should be open to young people, encouraging them to do more physical exercise," said an MOE official.