China will gradually build a comprehensive child welfare system to provide universal welfare protection to children, who are categorized into four types depending on their living circumstances, under a draft plan from the Ministry of Civil Affairs.

Children will be identified as orphans, in plight, from underprivileged families or from ordinary families. Each will be offered different standards of welfare services, the plan said.

More specifically, children in plight include those who are homeless, disabled or have serious illness. Children from underprivileged families are those whose parents are poverty-stricken, seriously disabled or ill, serving long prison sentences, are in compulsory drug rehabilitation, or single parents unable to raise the child alone.

There has been much concern about child welfare after a recent case in Nanjing, Jiangsu province - in which two toddlers left home alone by their drug addict mother were found starved to death - shocked the nation.

A pilot program will be launched in Kunshan, Jiangsu province; Haining, Zhejiang province; Luoning county, Henan province; and Shenzhen, Guangdong province, according to the plan.

Tang Rongsheng, director of the Shenzhen Social Welfare Center, welcomed the policy as the issue of children from problematic families has bothered him for years.

"Shenzhen implemented the policy for abandoned babies and orphans last year so that the local government could take good care of them under existing regulations - our current policy even makes it plain how foreigners can adopt a child in Shenzhen," Tang said.

"But a system regulating the temporary takeover of custody from problematic families is still desperately needed."

He said the policy should be as detailed as possible and issues such as how to define a "problematic family" and how to support them should be noted.

"It's a ticklish question for those children whose parents are still alive and there's no court in China that can guarantee me our welfare house will get custody after raising them for 10 and even 15 years," Tang said, adding his current solution is to sign an agreement with parents who aren't capable of raising their children and have the document notarized.

Yang Ping, a staff member at Shenzhen's non-government organization Min Ai Disabled Children's Welfare Center, said she hopes the policy would help children regardless of their place of residence. She is also concerned about how the policy is implemented because its details would be decided by local governments.

Experts say the system could bring more children under protection but it is still not comprehensive enough to cover all those who need help.

"The categorization missed at least two kinds of children - those whose parents are drug addicts but are not under compulsory drug rehabilitation, and who are mistreated by their parents," said Tong Xiaojun, a professor at China Social Work Research Center in the China Youth University for Political Sciences.

Tong suggested an effective method would be to establish a team of child welfare workers responsible for tracking the situation of every child.

Ultimately, China needs to push forward child welfare legislation to safeguard all children, she said.

China still faces numerous challenges in improving child welfare. Figures show 628,000 orphans were registered in 2012, a sharp rise from 2011, according to the China Child Welfare Policy Report released early this month by United Nations Children's Fund.

The report also said 2.8 million children are not receiving the compulsory education they are entitled to.