The authorities will bring in tighter controls of fetus testing -- which can be used to determine the sex of a fetus -- according to a document jointly issued by the Chinese Communist Party's central committee and the State Council, China's Cabinet.

"People who conduct illegal gender testing of fetuses and sex- selective abortions should face serious punishment," the statement said, according to Xinhua News Agency.

In China, where boys can be valued more highly than girls, female fetuses are sometimes aborted by families who want to make sure they have a boy. This has led to an imbalance in the number of boys to girls.

The problem is exacerbated by China's strict family planning policy that restricts most city dwellers to just one child.

China's gender ratio for babies born in 2005 was 118 boys for every 100 girls, according to Xinhua, compared with a ratio of 110-100 in In some regions the figure has even reached 130 boys for 100 girls.

Xinhua said this amounts to "a hidden danger" for society that will affect social stability. One of the problems faced by the more numerous boys when they grow up will be the difficulty of finding a wife.

There are currently rules in place to prevent parents finding out the sex of the fetus, but there are reports that those desperate to know sometimes find ways to circumvent these regulations.

News of the tough new stance was released the day before China is to officially announce policies relating to family planning and population control. It will be the third time the government has issued a major policy document on these issues.

The document is expected to examine problems resulting from China's growing population. Xinhua said this will peak at around 1.5 billion in 2033.

"Over the coming decades, China's overall population will increase by eight to 10 million annually, bringing unprecedented challenges to the country's social and economic development," Xinhua said.