(Updates with rebel factions squabbling)
By Denis Dumo
JUBA, March 16 (Reuters) - Gunmen have attacked an aid convoy in famine-hit South Sudan, killing two people and wounding three, the International Organization for Migration (IOM) said on Thursday.
The attack underscored the dangers confronting aid agencies in the world's youngest country at a time nearly half its population, or about 5.5 million people, face food shortages. The United Nations has already declared a famine in some parts.
South Sudan has been mired in a conflict that has split the nation along ethnic lines and forced more than three million people to flee their homes. Aid workers have been kidnapped, shot at and had their supplies looted by armed men.
The attack occurred on Tuesday near Yirol, in the centre of the country about 210 km (130 miles) northwest of the capital of Juba, where the aid workers had been dealing with a cholera outbreak.
In a statement, the IOM said the convoy was targeted as it returned to Yirol, with the gunmen ambushing one of the vehicles. Two people died of gunshot wounds, the aid group said, and an IOM health officer was among the wounded.
The identity and motivation of the attackers were unknown, the statement said.
Also on Thursday, medical charity Medecins Sans Frontieres (MSF) said its hospital in Wau Shilluk had been looted during recent heavy fighting.
"Wau Shilluk was looted of all medicines including life-saving drugs and essential supplies," Abdalla Hussein Abdalla, the deputy head of mission for South Sudan, said in a statement. "Our hospital is in a terrible condition."
Earlier this week, gunmen briefly detained eight local employees of U.S. charity Samaritan's Purse.
The civil war erupted in 2013 when President Salva Kiir, an ethnic Dinka, fired his deputy Riek Machar, a Nuer.
Machar's rebels, the Sudan People's Liberation Movement (In Opposition), on Thursday criticised a new rebel faction led by an army general who resigned earlier this year.
A statement allegedly released by the new rebel faction said that Machar's forces in the Equatoria region, near the Ugandan frontier, had pledged loyalty to former General Thomas Cirillo Swaka. "The SPLA IO is totally amazed and at the same time DISAPPROVES the claim of Thomas Cirillo that its forces in Equatoria region have pledged loyalty to him and his new faction," the statement said.
"We urge General Thomas to reconsider his strategy and not play into the hands of Salva Kiir's allies in the region, whose intention is to divide the opposition." (Reporting by Denis Dumo; Writing by Katharine Houreld; Editing by Alison Williams and Richard Lough)