South Sudan's warring factions have signed another peace deal to end hostilities.

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

Seyoum Mesfin, a mediator, says leaders of the regional bloc overseeing the talks will take severe action against anyone who breaks this latest agreement and report them to the African Union and U.N. Security Council.

Both the African Union and the Security Council have threatened sanctions against those undermining peace in South Sudan, the world's newest nation and one rich in oil.

Fighting broke out December 2013 between President Salva Kiir's troops and those loyal to former vice president Riek Machar.