South Sudan ceasefire broken as rebels and army battle

Both sides accused each other for a second day of attacking the other.

Fighting raged in the oil-producing state of Upper Nile, Defence Minister Kuol Manyang told AFP, adding that government troops had been ordered "not to go and attack, but only to fight in self defence."

Rebel forces said the army had attacked its positions in Unity state.

Since President Salva Kiir and rebel leader Riek Machar signed a deal Friday to halt fighting, both sides have blamed each other of launching ground attacks and artillery barrages.

Machar was "not in control of his forces" and heavily armed militia troops known as the White Army -- who smear themselves in wood ash to ward off mosquitoes and as war-paint -- had attacked government troops, Manyang said.

"These are irregular forces, the White Army is armed civilians, and they do not know about the cessation of hostilities agreement that was signed," he added.

"They are the ones that attacked, because they think the war is still going on."

Rebel spokesman Lul Ruai Koang said the army on Tuesday wrested back control of the flashpoint town of Bentiu -- which the government said it had already recaptured -- and charged the army with "indiscriminate, intensive and extensive shelling of surrounding villages with heavy artillery".

Army spokesman Philip Aguer said that monitors from regional bloc IGAD were being sent to Bentiu, capital of the northern oil-producing Unity state, which has swapped hands repeatedly in the conflict.

"We are working on their deployment, so that they can observe the situation on the ground," Aguer said.

- Risk of famine -

Kiir has insisted he wanted peace, telling crowds in Juba on Sunday that "we have ordered our forces not to lift a foot from where they are to attack rebels".

The two sides had agreed to a ceasefire in January, but that deal quickly fell apart and unleashed a new round of fierce fighting.

Observers have said both sides will face challenges in implementing a truce, with the rebels made up of a loose coalition of army defectors and ethnic rebels.

Each side accuses the other of using mercenaries and rebel forces from neighbouring Sudan, while on the government side -- backed by Ugandan troops -- the command structure under Kiir is also seen as weak.

The war in the world's youngest nation has claimed thousands -- and possibly tens of thousands -- of lives, with more than 1.2 million people forced to flee their homes.

The conflict, which started as a personal rivalry between Kiir and Machar, has seen the army and communities divide along ethnic lines, pitting members of Kiir's Dinka tribe against Machar's Nuer.

UN rights chief Navi Pillay, a former head of the UN genocide court for Rwanda, has said she recognised "many of the precursors of genocide" listed in a UN report on atrocities that was released last week.

The United Nations food agency has warned there is only a "small window of opportunity" to avert famine, and appealed for relief agencies -- who have been subjected to armed attacks and looting -- to be allowed unfettered access.

The war erupted on December 15 with Kiir accusing Machar of attempting a coup. Machar then fled to the bush to launch a rebellion, insisting that the president had attempted to carry out a bloody purge of his rivals.