Shandong police have rescued 37 infants after breaking up seven human trafficking gangs in the past two months, according to a China Central Television report.

A total of 103 suspects from the gangs have been detained for further investigation, said Xie Xinxi, director of the Jinan railway police department.

"The gangs sold the infants after they were born in underground delivery wards. An infant girl was sold for 60,000 yuan ($9,800) while a boy would bring 80,000 yuan," Xie was quoted as saying by CCTV.

The gangs also bought infants from rural areas in Sichuan and Yunnan provinces in recent months and sold them in Shandong and other coastal provinces.

"Only one infant girl has been reunited with her biological parents with the help of a DNA test," Xie said. "The other 36 may not be able to return to their parents because their mothers, who mainly come from the country's rural areas, sold them of their free will."

The 36 victims are now being cared for in children's welfare houses and foster homes. Most of them are in poor health because they were not cared for properly after they were born and were maltreated by the human traffickers.

Seven of them have even been found to be HIV-positive or diagnosed with syphilis or other sexually transmitted diseases passed on to them while they were fetuses.

Earlier this month, police swooped on a delivery room hidden in a derelict factory on the outskirts of Yanzhou, rescuing an infant and detaining seven suspects. Several pregnant women were also found in the underground delivery ward.

Chen Shiqu, director of the human trafficking task force under the Ministry of Public Security, said many human traffickers have introduced new methods to abduct and sell children to avoid the recent police crackdown.

"Directly abducting and selling newborns is one of the new methods that help the human traffickers to avoid detection," Chen said.

A 3-year-old girl is reunited with her mother after police in Shandong province broke up seven human trafficking gangs, a screengrab from a CCTV report shows.