The gender imbalance in the Chinese population is worsening, an official Chinese newspaper has reported.

Shanghai's Business Weekly quoted new figures from the country's top social research body, the Chinese Academy of Social Sciences, suggesting that the sex ratio of Chinese babies at birth was now 120 boys to 100 girls.

This is fuelling concerns that millions of Chinese boys are destined to become life-long bachelors.

Official sensitivity

Official sensitivity makes it hard to extract reliable figures on China's sex ratio from the relevant bureaucracies.

The Chinese Academy of Social Sciences would not confirm the figures to the BBC, saying it was not authorised to publish the results of its research.

Experts from the United Nations Population Fund said the last published nationwide figure is for 1995, when 116 boy babies were born for every 100 girls.

This sets China apart from most countries. The world average is about 106 boys to every 100 girls, with infant mortality higher among boys so the ratio evens up over time.

Traditional preference

Most population experts agree that China's problems are caused by a traditional preference for boys, along with two decades of strict family planning and the availability of sex selecting technology.

China now produces 10,000 ultrasound machines a year and although it's illegal to tell parents-to-be the sex of their foetus, the practise is commonplace.

Rural couples who discover that they are going to have a girl often choose to abort, especially if the child in question will be the second - and therefore subject to heavy fines for exceeding one child family planning restrictions.

The Chinese Government rarely draws attention to these problems because it does not want to undermine the family planning policy.

But gender imbalance is a familiar theme in the media, with reporters pointing to the numbers of women who are kidnapped and sold into marriage every year.