Chinese state media has reported that the country's one child policy is to be "loosened", in what would mark a major revision of a policy implemented over three decades ago.

The official Xinhua News Agency said the Communist party released a key document saying it will now allow couples to have two children, but only as long as one of the parents is an only child.

Since 1979 most Chinese families have only been allowed to have a single child. The policy was introduced as an effort to stop China's population - which is already approaching 1.4 billion people - from growing out of control.

The law has caused social problems, including uncertainty for the elderly who are left with no real safety net because four grandparents and two parents only have one caretaker for old age. There have been frequent allegations that the policy is sometimes violently enforced, leading to a variety of human rights violations. 

Xinhua also reported Chinese authorities will abolish a much-criticised labour camp system.

The "re-education through labour" system allowed police panels to sentence offenders to years in camps without a trial.

The announcements follow a meeting of the party's top leaders earlier this week.