The United Nations has appointed a special envoy for Sudan and South Sudan to help mediate remaining tensions between the newly-divided nations.

Secretary General Ban Ki-moon announced Friday the position would be filled by Haile Menkerios, who since last year served as the head of the U.N. mission in Sudan.

The statement said Menkerios has “extensive experience in African issues.” He has previously helped negotiate an agreement between the governments of Rwanda and the Democratic Republic of Congo regarding rebel groups operating in eastern DRC, as well as represented the Secretary General in the DRC and elsewhere in Africa.

Before joining the U.N. in 2002, Menkerios represented the Eritrean government in Ethiopia and Somalia, to the Organization of African Unity, and to the United Nations.

South Sudan declared independence on July 9, after a referendum agreed to in the 2005 peace agreement ending a two-decade-long north-south civil war.

But several key issues remain unresolved, including the fate of the oil-rich Abyei region, which was a key battleground during the war.

Both sides now claim the region, and the top United Nations peacekeeping official told the Security Council Wednesday the situation remains tense. But Alain Le Roy says Sudan and South Sudan both appear committed to avoiding an escalation in violence.

Le Roy said the U.N. had deployed 500 peacekeepers to the region Wednesday and by Sunday, he expected to send up to 1,200 of the eventual 4,200-strong force.