China sounded the alarm over the country's growing gender imbalance on Monday, vowing to improve protection of infant girls and ratchet up punishment for those who perform abortions based on the sex of the baby.

The measures highlight the leadership's increasing concern over the widening gender gap due to a traditional preference for male offspring and policies limiting most couples to one child that has made abortion a widely used method for controlling family size.

The imbalance is "a hidden danger" for society that will "affect social stability," the official Xinhua News Agency said, citing a statement issued jointly by the ruling Communist Party and the State Council, China's Cabinet.

It said people who "conduct illegal gender testing of fetuses and sex-selective abortions should face serious punishment." The statement also said the protection of baby girls should be improved by punishing those who kill, abandon or injure the infants.

No details were given.

According to Xinhua, 118 boys were born for every 100 girls in 2005. In some regions, it said, the figure hit 130 for every 100 girls. The average for industrialized countries is between 104 and 107 boys for every 100 girls.

The use of an ultrasound or other means to determine if a fetus is a boy or a girl is banned in China, but doctors who do so usually face only administrative penalties, not criminal charges. Many such checks are carried out by freelancers moving from village to village with only an ultrasound machine.

Abortions to select a child's gender are not currently outlawed. However, a family planning regulation prohibits the practice except for medical reasons. People who perform illegal scans or abortions face a minimum fine of 10,000 yuan ($1,255) or more based on their earnings from the procedure.

While narrowing the gender gap is a priority, China continues to stand firmly behind its three-decade-old one-child policy planning policy, Xinhua said. "The country is still facing huge challenges from a growing population," it said.

Beijing contends that the policy has helped prevent 400 million births and aided rapid economic development.

The government has pledged to keep the mainland population under 1.36 billion by 2010 and under 1.45 billion by 2020, Xinhua said. The current population is 1.3 billion.