Police in China have rescued 36 children who were being held in a huge trafficking ring, the latest swoop on a crime that is thought to involve tens of thousands of victims.

More than 157 people were arrested for their involvement in the ring, which spanned across several Chinese provinces, police said.

The suspects, who were held in raids from Fujian in the south-east, to Yunnan in the south-west, were believed to have already trafficked “dozens of infants” since 2014, reports said.

Media did not provide details on specific ages of those rescued, but Chinese state broadcaster China Central Television (CCTV) showed images of babies in its report.

Child trafficking is a major problem in China, particularly in poor rural areas.

Chinese media Caixin said that nearly half of all cases of children who are sold involve the consent of their own family, including parents who often sell their daughters for cash.

Poor communities in China often have a traditional preference for male offspring, who can carry on the family name and provide support to their elderly parents.

Most of the trafficked children in China are boys aged under six who are often sold for adoption, while youngsters aged between 14 and 18 are commonly girls, suggesting that they are being sold into prostitution, Caixin said.