Thirteen people were killed and 20 others injured during ethnic clashes in a camp for the protection of civilians of the UN mission in southern Sudan, according to the United Nations Agency for the Coordination of Humanitarian Affairs (OSHA) on Friday.

On Thursday, a 14-year-old boy from the Shilluk ethnic group was stabbed to death in Malakal camp, about 520 km north of the capital, Juba, in Upper Nile state.

The UN agency stated in a statement that this incident "caused the outbreak of ethnic violence," speaking of a total of "13 dead and 20 wounded."

This climate of insecurity impedes humanitarian activities, she said, noting the suspension of "the transfer of South Sudanese fleeing the conflict in Sudan from border points towards Malakal."

South Sudan gained its independence in 2011, but two years later it sank into a five-year civil war between rival rivals Riek Machar and Salva Kiir, which left nearly 400,000 dead and millions displaced.

The war officially ended in September 2018 with a peace agreement that stipulates the principle of power-sharing. But this agreement has been largely unimplemented, more than two years after the formation of a national unity government that included Kiir and his archenemy Machar, the current vice president.

The United Nations and the international community accuse South Sudanese leaders of maintaining the status quo, stoking violence, suppressing political freedoms and embezzling public funds.