China is vowing to harshly crack down on sex-selective abortion for non-medical purposes in order to balance sex ratio in a country that traditionally holds that male heirs can ensure their families' bloodline is preserved, according to a government plan released Monday.

The Outline for the Development of Chinese Children (2011-2020) says efforts should made to "eliminate discrimination against girls" and continue promoting gender equity.

"Using ultrasonic techniques to conduct non-medical sex determination" should be strictly prohibited, it says, adding that the economic and social status of rural families raising girls should be enhanced.

China has implemented family planning policies for about three decades that have restricted urban couples to just one child, while ethnic minority families are permitted to have more children.

Although the country's population has been controlled, illegal sex-selective abortions thrived in many parts of the country until the government launched several crackdowns.

Family planning policies have loosened over the years. In many parts of the country, couples made up of people from one-child families are permitted to have two children. In rural areas, couples are permitted to have a second child if their first child is female.

Guangdong Province, one of the country's most populated province, has already gone one step further. It recently submitted a proposal to the central government that will allow couples to have two children if even just one of the parents is a single child, said Zhang Feng, the province's family planning official.