Mainland society is becoming more unstable amid widening wealth disparity, despite strong economic growth, a government think-tank has found.

The gap is not only between urban and rural areas, but also between the rich costal cities and the poorer inland provinces, according to a compilation of studies released yesterday by the Chinese Academy of Social Sciences.

The warning comes as the academy projected a strong 9.3 per cent growth in the gross domestic product for this year, and 9 per cent for next year.

The rich-poor divide is fuelling crime and a dramatic rise in land disputes and clashes between the public and government officials over environmental issues.

The studies, "Analysis and Forecast on China's Social Development (2006)" or the Blue Book of Chinese Society, said social stability had worsened since 1980, with indicators for the crime rate, extent of corruption and production safety all showing a negative trend.

The Gini coefficient, an indicator of income disparities, reached 0.53 last year, far higher than a dangerous level of 0.4.

Social scientist Zhu Qingfang, in one of the articles, says 60 to 80 per cent of financial capital and savings are controlled by 20 per cent of the population, while the remainder lack the purchasing power to meet their consumption needs.

"The rich-poor disparity has led to the intensification of social disputes, mass protests, and criminal cases," she wrote.

The study found that although the net income of farmers grew by  6 per cent, after discounting inflation and the rising cost for fertilisers and other investment for production, in 2005, it still lagged behind the net income increase of 9 per cent for urban residents.

In terms of net income, the urban-rural gap has expanded from a ratio of 3.2:1 last year to 3.3:1 this year, according to the study.

Sociologist Lu Xueyi writes in the report that the huge income gap between urban residents and 140 million rural migrants working in the cities also gave rise to social conflict and crimes.

About 70 per cent of the suspects arrested for criminal offences in cities were migrant workers, he said.

One of the editors of the compilation, Li Peilin , said public anger was rising against those who got rich from ill-gotten gains.

"Not only is the low income group not satisfied with their income, the middle income group is not satisfied either," he said.

The uneven distribution of education and health-care services are identified as the two major causes behind social disparities.

Taking into account the government expenditure in education and health services, urban residents were six times better off than rural residents, Dr Li said.

The book also highlighted land disputes and pollution as two major sources of conflict.

"Land has become the major source for development and government income. There are large conflicts in many areas," Dr Li said.

Earlier this month, a riot was triggered by land seizures in the village of Dongzhou, Shanwei in Guangdong. The local government has put the death toll from the riot at three, but villagers fear the real figure could be as high as 20 because many villagers are still missing.

Protests caused by environmental issues grew by 11.6 times over the past 10 years, with an annual growth rate of 28.8 per cent. A third of the clashes over pollution this year turned violent, as farmers burned or smashed government property.

The study also warns of the rapidly ageing population, the number of elderly is set to reach 140 million this year. One in six of those who are above the age of 60 are classified as poor.

Another danger the mainland faces is the mounting debts held by universities.

It said tertiary institutions have borrowed a total of 120 billion yuan to 200 billion yuan from banks, while some institutes may be facing debts of up to 2 billion yuan.