Sketched in 2003, the plan provided for a five-year transition period in Morocco's Southern Provinces, known as the Sahara, followed by a self-determination referendum. The plan was rejected by Morocco and by several observers who described it as "outdated".
James Baker's plan, Ki-moon said, did not trigger the desired process "because of several divergences between the parties."
The dispute broke out in 1976 when the Polisario laid claims to the Sahara; a former Spanish colony Morocco retrieved a year earlier under the Madrid Accords signed with Spain and Mauritania.
The UN top official voiced hope “the problem will be settled through dialog between the concerned parties,” and to “see the parties start talks for a peaceful settlement” of the dispute.