As the army in southern Sudan has pledged to end the use of child soldiers by the end of the year, a UN special envoy on Wednesday expressed her concern about recruitments that could be renewed at time of war.

The Sudanese government Tuesday launched a program to end the use of child soldiers by the Sudan People's Liberation Army (SPLA) with the SPLA signing an action plan to release all children in its ranks by November and end the exploitation of children as soldiers across southern Sudan.

"The actual plan says child soldiers cannot be recruited, but we can't say what will happen if a war breaks out," Radhika Coomaraswamy, the UN secretary-general's special representative for children and armed conflict, told Xinhua in a phone interview Wednesday.

To take charge of the demobilization, the SPLA set up a child protection unit that needs to ensure that no children will be left in the ranks of the SPLA or work with partners during the verification, registration and demobilization of children still associated with the SPLA.

"What we told the SPLA is to hand them over to child protection groups and try and reunify them with their families," Coomaraswamy said.

About 900 children between 10 and 18 years old are expected to be released, the United Nations Children's Fund (UNICEF) estimated.