More than half of primary and lower secondary age children in South Sudan are out of school, while 40% of children in Sudan are out of school, UNICEF said Tuesday.

The group said 24 million children worldwide are out of school in countries experiencing conflict.

In South Sudan, 413,000 children were forced out of school during the latest civil war, in addition to 1.4 million children out of school before the conflict broke out, the group said. More than 800 schools were destroyed in the violence.

“Education cannot wait - it is the smartest investment for a peaceful and prosperous South Sudan,” said Jonathan Veitch, UNICEF Representative in South Sudan. "Children in South Sudan have lost their homes, family members, friends, safety, and routine. Education is key to ensuring they don’t also lose their futures.”

UNICEF appealed for 25 million US dollars in donations to get out of school children back to learning in South Sudan. The group said 360,000 children were already put back in school through the end of 2015.

Other countries in conflict with many children out of school include Niger, where 47% of children are not in class, and Afghanistan, where 40% of children are missing out on education, UNICEF said.

UNICEF photo: On 10 August, a young boy writes in his maths book in the Tomping Protection of Civilians site, on the base of the United Nations peacekeeping mission in South Sudan (UNMISS) in Juba, the capital.