Police have detained two officials including one involved in family planning in China's latest crackdown on child trafficking that has ensnared 355 suspects, state media said Wednesday.

Officers from nine regions took part in the joint crackdown beginning December 18 against the nation's trafficking networks and rescued 89 children, the public security ministry said in a report earlier this week.

Among the suspects was a family planning official surnamed Wang, who was arrested in the southeastern province of Fujian and is being charged with trafficking four babies, the Global Times newspaper reported Wednesday.

Police also arrested another official in Fujian after he and his wife purchased a baby boy, the report said. The couple already have a 10-year-old son.

Photos showed masked nurses in a hospital in the southwestern province of Sichuan taking care of some of the new-born babies who were rescued.

Police also released numerous photos of the suspects, including several young woman as well as a mother who was arrested with her child.

Chinese academics have long blamed the country's "one-child" policy for contributing to child trafficking. This aims to control growth in the world's largest population now standing at 1.3 billion.

It generally limits people in urban areas to one child, while rural families can have two if the first is a girl. This has put a premium on baby boys, and girls have been sold or abandoned as couples try for a male heir.

"In some cases, family planning officials sell the children," the Global Times quoted Zhang Shiwei, a campaigner against child trafficking, as saying.

"Police are also bribed by people who need to register a hukou, or household registration permit, for their purchased baby."

Family planning officials who have previously been convicted of trafficking are often involved in persuading couples who have violated the population control policy to give up their baby for adoption.

The children are then sold to trafficking rings and have sometimes even found their way into state adoption centres that supply orphans to foreign parents, state media reports have said.

Of the 89 children rescued in the ongoing campaign, five have been returned to their parents, while the others are undergoing DNA testing in an effort to locate their families, the Fuzhou Evening News reported.

Police have said they rescued more than 24,000 abducted children and women last year, some of whom had been sold for adoption or forced into prostitution as far away as Angola.