Chinese authorities say they broke up a human trafficking ring involving poor migrant couples, who were selling their babies through brokers.

The state-run Global Times newspaper said Friday that police in eastern Shangdon province's Zoucheng city found last month that 17 babies had been sold in the city.

The article said police rescued 13 of the babies and sent them to welfare centers, and a search is underway for the other four.

The paper said baby boys could be sold for up to $7,730, while the price for girls was $4,725.

China's one-child policy sets the stage for a thriving child market, mostly involving buyers who want more children or who want them as slave labor.