"Reopening the results of the election would be a grave injustice and set an unfortunate predecent," Ban said during a close-door meeting late Saturday in the Ethiopian capital ahead of an African Union summit.

Ivory Coast has been gripped by a political crisis sparked by the disputed November presidential poll run-off which showed incumbent leader Laurent Gbagbo defeated by rival Alassane Ouattara to whom he has refused to relinquish power.

The UN, the African Union and other world powers recognise Ouattara as the winner of those polls and have piled pressure on Gbagbo to leave.

Gbagbo has previously called for a recount, a move rejected by Ouattara, while some African leaders against the use of force to dislodge Gbagbo have also called for an investigation into the disputed polls.

During the two-day Addis Ababa summit, African leaders will seek a common ground to end the Ivorian crisis.

The pan-African body on Friday announced the setting up of a five-member heads of state panel to make binding recommendations on the Ivory Coast rivals.

Ban underlined the importance of a "peaceful and honorable exit" for Gbagbo, and urged "President Ouattara to form a national unity government."

AU Commission chief Jean Ping said Saturday the panel would help Ouattara "exercise power" through a negotiated deal.