More than 650 children have been recruited as soldiers by armed groups in South Sudan this year, according to UNICEF.
The fear is that many more children will be forced to fight because of renewed conflict in the capital, Juba, and other parts of the country, says UNICEF spokesman Christophe Boulierac.
"When children are faced by armed groups or forces, they suffer immense physical and psychological long-term damage,” Boulierac said. “We fear that a further spike in child recruitment could be imminent. We call for an immediate end to recruitment and the unconditional release of all children by all armed actors."
An estimated 16,000 children have been recruited as soldiers since war between the government and rebel groups broke out in December 2013. Last year, UNICEF oversaw the release of 1,775 former child soldiers.
It says it is very concerned that renewed fighting is undermining last year’s progress and putting tens of thousands of children at risk.
In addition, Boulierac says, a large number of women and girls have been subjected to sexual violence since fighting broke out July 8 in Juba.
"The systematic use of rape, sexual exploitation and abduction as a weapon of war in South Sudan must cease together with impunity of all perpetrators,” he said. “It is also important to note in South Sudan that while women and girls represent a majority of those affected, cases of men and boys being raped and sexually assaulted have also been reported."
As the South Sudan conflict moves toward the three-year mark, UNICEF reports that fighting has killed nearly 1,200 children. In addition, more than 13,000 children are missing, have been separated from their families or are unaccompanied.