Talks to resolve tension between Sudan and South Sudan have entered a second day, after negotiations ended in shouting Tuesday.

A VOA correspondent at the scene, in Ethiopia's capital, Addis Ababa, reports the talks are in a delicate stage as the sides try to resolve simmering disputes over oil, borders, and citizenship issues.

Talks on the status of southerners living in the north turned into a shouting match Tuesday. A participant said those particular talks are probably over for now, though the sides continue to discuss the oil and boundary disputes.

On Tuesday, the U.N. Security Council expressed “grave concern” about reports of troop movements and airstrikes along the poorly-defined Sudan-South Sudan border, and demanded that all parties cease military operations in the area.

The council also urged the countries to respect a non-aggression pact they signed less than a month ago.

The African Union is mediating what are scheduled to be 10 days of talks between Sudan and South Sudan.

Much of the tension between the countries stems from the oil dispute. The south took over most Sudanese oil production when it became independent last July but is refusing to pay what it considers excessive fees to use northern pipelines. The landlocked south needs the pipelines to send the oil abroad.

The dispute has prompted South Sudan to shut down all oil production, a move analysts say is likely to financially hurt both countries.

The sides also disagree on borders of the oil-producing Abyei region, and accuse each other of supporting the other's rebel groups.