Twin baby girls allegedly stolen and sold by the obstetrician who delivered them in China have been recovered by police, state media reported Friday.

The girls, born last month in the northern province of Shaanxi, were allegedly victims of the same female doctor who sold a baby boy reunited with his parents earlier this week.

The obstetrician, Zhang Shuxia, told the twins' mother in the delivery room that her babies had "deadly congenital diseases" and convinced her give them up, China National Radio reported.

Zhang also said their arms and legs were "broken" and stopped other relatives seeing them, the report added.

Similar details were described in reports this week about the boy, who police said was sold to a farmer with three daughters in the central province of Henan by alleged traffickers for 60,000 yuan ($9,800).

The doctor and two other suspects were detained after the boy's family became suspicious and reported their case to police. The blaze of publicity surrounding his recovery has prompted a wave of others to come forward.

One of the girls was found in Shandong province, more than 500 kilometres (310 miles) from her birthplace in Fuping county, and her sister around 160 kilometres away in Shanxi province, the website of the People's Daily said citing local authorities.

So far five officials have been sacked in Fuping, including the director of the county's health department and the head of the hospital where the children were born, the official Xinhua news agency said.

Police had received reports of 55 possible incidents by Thursday, including 26 allegedly involving Zhang, it added.

Lou Qinjian, governor of Shaanxi, on Thursday called the case "vile" and vowed to punish those responsible "seriously", it said.

Fuping is the home county of the family of Chinese president Xi Jinping.

Trafficking of children is a serious problem in China, blamed in part on the "one-child" policy which has put a premium on baby boys, with girls sometimes sold off or abandoned.

Under the policy, aimed at controlling China's vast population of more than 1.3 billion, people who live in urban areas are generally allowed one child, while rural families can have two if the first is a girl.

In a much publicised case, Chinese police rescued 89 children and arrested 355 suspects in December after breaking up a series of child trafficking rings.