The U.N. Security Council is demanding that Sudan and South Sudan take steps to prevent war, as the sides begin a new round of talks in Ethiopia.

The two Sudans are locked in a bitter dispute over oil, and accuse each other of supporting the other's rebel groups.

Ambassador Mark Lyall Grant of Britain, which holds the rotating Council presidency, said Tuesday the Council is gravely concerned about reports of troop movements and airstrikes along the border.

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

“The Security Council demands that all parties cease military operations in the border areas and put an end to the cycle of violence.”

The Council also demanded that Sudan and South Sudan “take no action that would undermine the security and stability of the other.”

The statement came as Sudan and South Sudan began a scheduled 10 days of talks in Addis Ababa. The African Union is trying to mediate disputes centered on oil revenue sharing, the undemarcated border, and citizenship questions raised by South Sudan's independence in July.

The south took over most Sudanese oil production but is refusing to pay what it considers excessive transit fees to use northern pipelines. The landlocked south needs the pipelines to send the oil to international markets.

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

The sides are also in disagreement over borders of the oil-producing Abyei region.

A previous round of talks last month yielded no progress, except for the non-aggression pact.

When Sudan was a unified country, the north and south fought a bloody 21-year civil war.