PARIS - Far more people in China suffer from mental disease than previously suspected, with most going untreated, according to a major study unveiled Friday.

The largest health survey of its kind ever conducted in China estimates that 173 million adults have some type of mental disorder, and that 158 million of them - 91 per cent - have never received professional help.

In many middle-income countries, including China, neuropsychiatric conditions are the leading cause of ill health in both men and women, easily outstripping infectious and cardiovascular disease, according to the study.

But relatively few resources are available for the mentally ill in China, partly because their numbers have been so seriously underestimated, the study contends.

To help provide such data, researchers led by Michael Phillips of Beijing Hui Long Guan Hospital conducted a survey - adapted from the so-called General Health Questionnaire - of more than 63,000 randomly selected individuals in four provinces.

Qinghai and Gansu in the west are among China's poorer regions, while Shandong and Zhejiang, both coastal provinces, are more urban and wealthier.

Of those questioned, 16,577 were also interviewed by a psychiatrist. All the data was collected between 2001 and 2005.

Overall, the study, published in the British medical journal The Lancet, showed that 17.5 per cent of adults suffered one or more mental disorders for at least one month during that period.

Earlier, less comprehensive, studies had suggested that the prevalence of mental disease was two to 15 times less.

Among women, mood and anxiety disorders were more common, while men were 48 times more likely to suffer from alcohol-related problems.

China is the only country in the world in which the suicide rate - well above the global average - is higher for women than for men, according to the World Health Organisation (WHO).

Rural dwellers were also more likely to have depressive disorders and drinking problems than their urban counterparts. Some 60 per cent of China's 1.3 billion people live in the countryside.

A quarter of those surveyed said they were either 'moderately' or 'severely' disabled by their illness, but only five per cent reported ever seeing a mental health professional.

"A major redistribution of societal and health resources is needed to address a problem of this size," the researchers concluded.

"This will only happen with the active participation ... of powerful political, economic, social and professional stakeholders." -AFP