Nearly 2,000 officials in central China have violated the nation's "one child" family planning policy, further revealing difficulties in implementing population controls.

Family planning departments have exposed 1,968 officials in populous Hunan province who have breached the law, Xinhua news agency said Sunday.

One "national" level official surnamed Li even went so far as to sire four children with his four different mistresses, the report said.

The local family planning commission caught 21 national and local legislators, 24 political advisers and 112 businessmen violating the birth control policies in the province that boasts a population of 66 million.

Many violations were uncovered as the officials and businessmen were investigated for corruption, it added.

China's family planning policy began in the late 1970s as a way to control a population that has grown to 1.3 billion people, the world's largest.

Generally, urban families can have one child and rural families can have two if the first is a girl.

But in recent years the policy has been routinely ignored in rural areas, while the newly rich in Chinese cities have opted to pay fines and suffer social penalties in order to have more than one child.

"It is estimated that the policy has prevented the birth of millions of people over the years, avoiding an explosive growth in China's population," Xinhua said.

"However, there have been increasing reports of officials, tycoons and entertainment stars having more than one child, causing grave public concern."

In May, a string of riots erupted in rural areas in the Guangxi region neighbouring Hunan, after local government teams began forcefully confiscating property as a way of penalising families who violated family planning policy.

Enforcement teams were also accused of forcing abortions and sterilisations on women who had more than two children or who gave birth without having the proper documentation.