South Sudan's warring factions early Monday signed another deal in the latest effort to end hostilities that have raged for more than a year.

South Sudanese President Salva Kiir and the opposition commander Riek Machar signed a power-sharing agreement, edging closer to a final deal to end a 15-month conflict that has ravaged the world's newest country, which is also one of the poorest depsite oil reserves.

The government and the opposition have previously signed at least three peace deals, which were broken quickly.

Leaders of the eight-nation regional bloc overseeing the talks, the Intergovernmental Authority on Development (IGAD) warned of severe action against anyone who breaks this latest agreement and vowed to report them to the African Union and U.N. Security Council, said mediator Seyoum Mesfin.

Both the African Union and the Security Council have threatened sanctions against those undermining peace in South Sudan.

The conflict erupted in December 2013 and has largely pitted Kiir's Dinka ethnic group against Machar's Nuer group.

Since the conflict began, thousands of people have been killed and more than 1.8 million have fled civil war sparked by a power struggle between Kiir and Machar. Last year, aid workers warn of the risk of famine if the conflict continued. The United Nations has said the food crisis in the country is the "worst in the world.”

Under the agreement sign Monday, Kiir would remain president in a new administration while Machar would be appointed vice president, two IGAD diplomats Reuters.

The two leaders have agreed to resume talks on Feb. 20, Mesfin said prior to the signing ceremony Addis Ababa, Ethiopia’s capital.

"[Those talks] would be final and that would lead them into concluding a comprehensive agreement to end the crisis in South Sudan," Mesfin said.

After signing the latest agreement, Machar said "This is a partial agreement because we have not solved some of the most critical issues," Machar said after the signing, citing disagreements on the "transitional government structure" to set up and divide responsibilities within the administration.

The two sides need a transitional government in place by July, when Kiir's presidential term runs out.

Al Jazeera and wire services