Ms Bang Mi Sun is a refugee from North Korea who was sold to three different men in China over a span of two years to become their wives.

She now walks with a limp. Her captors ripped chunks of flesh from her legs amid constant abuse such as beatings with sticks.

Ms Bang, in her 30s, had crossed the Tumen River into China in 2002 with her son and daughter in search of food. The guide sold her to a disabled Chinese man for US$585 (S$811) who then resold her to other men. Her last husband was 14 years younger than her and demanded that she bear him a son.

She was separated from her children by the traffickers and has not seen them again since.

Ms Bang managed to escape to South Korea in 2004, and was later taken by the United States-based non-profit Polaris Project on Human Trafficking to Washington, DC, where she told her horrific story to the National Press Club in May last year.

She is just one of thousands of women sold to Chinese men, mainly in rural areas where men greatly outnumber women.

There are no official figures on the number of brides taken to China and sold. Prices range between 2,000 yuan (S$406) and 40,000 yuan - depending on their age and looks. Most are from North Korea, Vietnam and Myanmar, and come seeking a better life in China.

The demand for foreign brides is likely to grow as the surplus of men widens, say experts. They warn that China may become a top destination for human trafficking.

A manager surnamed Li from Harmony Bliss, a Guangzhou-based match-making agency that organises tours for Chinese men to neighbouring countries to choose wives, said that he expects business to 'grow rapidly' in future.

'We've already been getting 30 per cent more queries in the past year,' he said.

Chinese women and girls as young as two years old have also become victims of bride traffickers. From April to December last year alone, more than 7,300 Chinese women who had been kidnapped and were about to be sold as brides were rescued by the police.

To combat the growing problem, China has embarked on a four-year national plan involving more than 30 government departments.

Measures include setting up websites to highlight missing women and girls, and working with the public and netizens to spot suspicious activities by bride-trafficking gangs.

Additional reporting by Lina Miao

This article was first published in The Sunday Times.