London: Tens of thousands of North Korean women and girls – some as young as 9 – are being trafficked into sexual slavery in China as they try to flee poverty and oppression in their homeland, experts on the reclusive state said on Monday.

The sexual exploitation of North Koreans generates at least $US105 million ($153 million) in annual profits for the Chinese underworld, according to a report by the non-profit Korea Future Initiative, which includes harrowing accounts from trafficked women.

A new report details the extent to which North Koreans fleeing poverty are being trafficked into sexual slavery. Credit:AP

"Victims are prostituted for as little as 30 Chinese yuan ($6.30), sold as wives for just 1,000 yuan, and trafficked into cybersex dens for exploitation by a global online audience," the report's author Yoon Hee-soon said.

"Many are sold more than once and are forced into at least one form of sexual slavery within a year of leaving their homeland."