South Sudan rebels confirm heavy fighting in north

South Sudan's civil war began in the capital Juba in December 2013 and has since spread across the country killing at least 50,000 people and forcing more than a million from their homes (AFP Photo/Simon Maina) (AFP/File)

Addis Ababa (AFP) - South Sudan's rebels confirmed Tuesday they were engaged in renewed heavy clashes with government forces in the country's oil-rich north, but accused their rivals of initiating the fighting.

The statement came the day after the government claimed it had killed scores of rebels after they attacked around the town of Renk in Upper Nile State, in what appeared to be some of the worst violence since peace talks broke down earlier this month.

Rebel military spokesman Lony Ngundeng, however, accused government troops of launching an attack on their positions. He said the government troops suffered heavy losses, including "many fighters" who drowned in the White Nile river.

Aid sources have confirmed fighting in the area close to the border with Sudan, but could not give any further details.

South Sudan's civil war started in December 2013, when President Salva Kiir accused Riek Machar, who had been sacked as vice president, of attempting a coup.

The two sides have been locked in sporadic and often intense fighting since, leaving tens of thousands of people dead, two million uprooted from their homes and 2.5 million in desperate need of food aid.

Regionally-brokered peace talks in Ethiopia's capital Addis Ababa collapsed earlier this month, with diplomats now warning of the possibility of targeted sanctions against military leaders from both sides.