China will also abolish its notorious labour camps in an effort to improve human rights, the state media reported, quoting key decisions issued by the CPC.
"China will loosen its decades-long one-child population policy, allowing couples to have two children if one of them is an only child," Xinhua news agency reported.
China, which has a population of over 1.3 billion, will implement this new policy while adhering to the basic state policy of family planning, the report quoted a decision approved at the Third Plenum of the CPC Central Committee held in Beijing from November 9 to 12 chaired by Chinese President and CPC General Secretary Xi Jinping.
The birth policy will be adjusted and improved step by step to promote "long-term balanced development of the population in China," it said.
China's family planning policy was first introduced in the late 1970s to rein in the surging population by limiting most urban couples to one child and most rural couples to two children, if the first child born was a girl.
The policy was later relaxed, with its current form stipulating that both parents must be only children if they are to have a second child.
Other reforms announced today include the abolition of "re-education through labour" camps.
The network of camps created half a century ago holds thousands of inmates.
Police panels have the power to sentence offenders to years in camps without a trial.
China's leaders have previously said they wanted to reform the system.
The decision to do away with the camps was "part of efforts to improve human rights and judicial practices", Xinhua said.
According to the latest available figures from the Ministry of Justice, 160,000 people were held in 350 re-education through labor centres nationwide at the end of 2008
The United Nations has said the figure is possibly as high as 190,000 people.
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