China is to ease its family planning policies and abolish a controversial labour camp system, according to a key document issued after a ruling Communist Party meeting.

Couples will be allowed to have two children if one of the parents is an only child.

This is part of an adjustment of the birth policy to promote "long-term balanced development of the population in China", it said.

Previously, a couple could only generally have a second child if both parents were only children.

China's one-child policy has resulted in a massive gender imbalance, with 117 newborn boys for every 100 girls. 

There are an estimated 40m single men in China as a result of the policy. 

The reform package will also see China abolish the labour camp system, which it calls re-education through labour, and reduce the number of crimes subject to the death penalty "step by step", Xinhua News Agency added.