A population expert has called on lawmakers to make it a criminal offence to identify the sex of an embryo for non-medical purposes and also to outlaw abortions that are not medically justified.

Wei Jinsheng, a researcher with the China Population and Development Research Centre, said in an article published in the latest issue of Qiushi (Seeking Truth from Facts) magazine that the National People's Congress (NPC) should incorporate provisions banning sex selection for non-medical purposes in the country's Criminal Law.

The rising gender imbalance is posing a serious threat to society's smooth development, Wei said.

Statistics indicate that 117 boys are born for every 100 girls in China, well above the international average of 107 boys to 104 girls.

The underlying reason for China's rising gender imbalance is the entrenched idea that boys are better than girls. The idea has its origin in rural China where farm work prefers men, deemed physically stronger than women.

Ultrasound technology allows prospective parents to learn the sex of an embryo, which means that they sometimes choose to abort particularly in rural areas when the embryo is female.

Although it has been a rule within the Chinese medical community to not divulge to pregnant women their embryos' sex, it has not been instituted as a criminal offence.

A draft amendment to the Criminal Law submitted to the Standing Committee of the NPC for review earlier this year would institute penalties of up to three years in jail, probation and fines for those involved in gender identification of embryos for non-medical purposes.

But the provision was later removed because lawmakers were divided on the provision. Opponents say it is a woman's right to know her baby's sex.