South Sudan's government and rebels are accusing each other of breaching a ceasefire just hours after it came into effect, dealing an early blow to hopes for an end to a five-month civil war.
The rebels on Sunday accused government soldiers loyal to President Salva Kiir of launching ground attacks and artillery barrages against their positions in two oil-rich northern states, including near the key hub of Bentiu.
The government insisted the rebels attacked first and that it killed around 27 fighters in the morning fighting.
President Kiir also accused rebel leader Riek Machar of having been opposed to the peace deal signed in Addis Ababa.
"The violations ... shows that Kiir is either insincere or not in control of his forces," rebel military spokesman Lul Ruai Koang said of the president.
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Kiir and rebel leader Riek Machar met in the Ethiopian capital on Friday and agreed to halt fighting within 24 hours - or by late Saturday evening.
Independent witnesses said fighting broke out by dawn Sunday around Bentiu - the Unity state capital which has changed hands several times in recent weeks - but that it was impossible to say which side fired first.
The rebels said government troops also attacked in neighbouring Upper Nile State, and that they reserved "the right to fight in self-defence".
But South Sudan's defence minister, Kuol Manyang, told AFP it was the rebels who attacked first in Bentiu and that the opposition suffered heavy casualties.
Kiir also insisted he wanted peace, telling a crowd in Juba that "we have ordered our forces not to lift a foot from where they are to attack rebels".
He said, however, that Machar only signed the deal "under pressure".
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 side will face challenges in implementing a truce, with the rebels made up of a loose coalition of army defectors, ethnic rebels and, allegedly, mercenaries from Sudan.
On the government side, the command structure under Kiir is also seen as weak.
The peace deal signed on Friday came after massive international pressure to stop a war marked by widespread human rights abuses, a major humanitarian crisis and fears the world's youngest nation was on the brink of a genocide and Africa's worst famine since the 1980s.
