A criminal gang in northern China bought intellectually disabled women from their families and kept them in a pigsty from where they were sold as brides to men from impoverished areas. The gang is believed to have netted more than 600,000 yuan (£60,000; $94,000) over two years.

The Shandong based gang sold ten women for between 50,000 yuan (£5,000; $8,000) and 100,000 yuan each, reports the South China Morning Post. The women were bought from their families in Guangdong province and the Guangxi region in southern China for 3,000 yuan to 5,000 yuan on the promise that they would be married to well- off suitors.

In China, men typically have to provide a 'bride price' starting at 100,000 yuan to prove they are eligible for marriage.

The gang was exposed when two men travelling with one of the women on a train from Guangxi to northern China attracted the attention of police and were arrested. Under questioning, they told police about the criminal operation.

Police found that a man named by police as Sun would find prospective buyers from impoverished rural communities in Shandong. He would then alert a middleman, who would find intellectually disabled women and buy them from their families in southern areas.

The women were then kept in a pigsty in Shandong where prospective buyers would choose their 'brides'.

The buyers were usually older men from poor villages unable to find a bride, according to the report. The women were usually 20 to 30 years old, and were considered a burden by their families.

An officer said that the gang earned more than 600,000 yuan over two years from the sale of the women. The women's families did not try to make contact with the women after they were sold, and in one case a family would not take a woman rescued from the gang back until local authorities had agreed to provide a subsidy to help with her upkeep.

As a result of China's one child policy, there is a significant gender imbalance, with 118 men for every 100 women. The high cost of dowries and the impoverishment in rural areas means that some Chinese men search for wives in southeast Asian countries including Cambodia and Vietnam. Gangs also illegally traffic women to be sold as brides in China.