The UN Security Council warned Tuesday that it was ready to "act immediately" if South Sudan's president does not sign a peace deal.

President Salva Kiir is scheduled to sign the power-sharing agreement in Juba on Wednesday, alongside the leaders of Kenya, Uganda, Sudan and Ethiopia.

Council members "expressed their readiness to act immediately if President Kiir does not sign the agreement tomorrow as he has undertaken," said Nigerian Ambassador Joy Ogwu, who chairs the council this month.