The UN chief has also called on leaders attending the African Union summit in Kigali to find ways of restoring peace in South Sudan. His call comes as the African Union's Commissioner for Peace and Security Smail Chergui says there are more than enough troops in South Sudan.

"We were hoping to have a different rule of engagement for African troops who are within UNMISS in a way to have the same approach like the one in MONUSCO where we have an African brigade just to be a force that can act to separate the two parties when we have a crisis. That point of view wasn't retained but now we have again to consider what will be the response because at the moment I think we have enough troops in South Sudan. Lets see how we can deal with this matter in an urgent way," he said.