A South Sudan rebel leader has called on President Salva Kiir to resign along with all ministers and the parliament or risk sparking a revolution.

Riek Machar said Wednesday that Kiir's term in office and that of the legislature expires at midnight according to terms of the 2011 transitional constitution.

Machar says if Kiir refuses to resign, citizens have the right to overthrow his government.

Fighting broke out in the world's newest nation in December 2013 after Kiir, an ethnic Dinka, accused Machar, an ethnic Nuer, of trying to oust him in a coup. That sparked months of ethnic attacks and the violence has continued despite several cease-fires.

The U.N Security Council last week imposed travel bans and asset freezes on six generals from both the government and rebel sides.