Myanmar has made significant progress in curbing the use of child soldiers, according to a UN report, but still faces challenges to completely root out the recruitment of children.

Since Myanmar’s reformist government signed an agreement with the United Nations to end the recruitment of children under the age of 18 to serve for armed forces, the number of reported cases of child soldiers declined to 32 in 2012 from 172 in 2009.

But the report also said the use of child soldiers still persists among armed groups including Kachin, Karen, Shan State and Wa State rebel groups.

The most vulnerable to underage recruitment are unaccompanied children and orphans found in workplaces, on streets, at bus and train stations, ferry terminals, markets and in their home villages. The majority of recruited child soldiers were aged 14-17, but “children as young as 10 years old have also been reported to have been recruited,” according to a monitoring task force.

United Nations Secretary-General Ban Ki-moon urged Myanmar to put an end to the recruitment of child soldiers by closing a loophole that allows the recruitment of 16-year-olds who have finished 10th grade and obtained special authorization from the Office of the Adjutant General to join the army, reports The Associated Press.