China has arrested a gang that ran an illegal business enabling women to identify the sex of unborn children and abort those they did not want, the country's Health Ministry said.

The crackdown netted 10 people who had since 2010 operated the service, the ministry said on Sunday. The operation sent women from all over the country to a clinic in the central city of Zhengzhou to find out the sex of their unborn child.

Last year alone, more than 1,000 women used the service, the ministry said, although it did not say how many abortions resulted.

Three decades of the "one child" policy in China have bolstered a traditional favouring of male offspring, seen as the main support of elderly parents and heirs to the family name. This led to abortions, killings or abandonment of girls and trafficking of both male and female children.

One of the business's ringleaders has already received a jail term of 3-1/2 years and fined 100,000 yuan ($16,500), with the rest getting slightly shorter sentences.

The ministry said it was the biggest case of its kind in the past few years.

"This went on for a long time, covering a wide area and involved many people. It was malicious, had serious results and was a great threat to society," it added.

The problem is widespread, the ministry warned, adding that it faced a "serious situation" in trying to end such abuses.
The government has tried for years to address the issue, which has led to serious population imbalances in some parts of China, particularly its wealthy coastal provinces.

Last week a court handed down a suspended death sentence for a doctor who sold seven newborns to human traffickers, in a case that ignited anger over rampant child trafficking.

The imbalance has created criminal demand for abducted or bought baby boys, but also for baby girls destined to be future brides, attracting rich dowries in parts of the country where there are too few women for all the men seeking wives.

While the government late last year announced a relaxation of its "one child" policy, many curbs remain, with Beijing saying family planning is still a key way to ensure China does not produce too many children to burden limited resources.