South Sudan Jonglei attack by Athor rebels 'killed 200'
Some 200 people were killed in a "massacre" in south Sudan last week, officials say.
Most of the dead were civilians, including children and others chased into a river by rebels, a minister said.
Previous estimates said that about 100 people had died when fighters loyal to rebel leader George Athor attacked.
The deaths come as the region prepares for independence from the north after last month's referendum.
Some 99% of people voted to secede from the north.
A senior official of south Sudan's ruling party accused the north of backing the rebel attacks.
The north has denied previous similar accusations.
The referendum on independence for the oil-rich south was part of a deal to end decades of north-south conflict.
The south's Humanitarian Affairs Minister James Kok, who has just returned from the area, told the AP news agency that 201 people, had been killed in what he termed a "massacre".
"They were chased into the river. I was the one who put them into a mass grave," he said.
He said nearly 160 of the dead in the two days of fighting last week were civilians, such as children, the elderly, refugees and several priests.
Another senior official said 197 people had died in the fighting in Jonglei, the south's most populous state.
Mr Athor blames the clashes on the southern army.
He took up arms last year, alleging fraud in state elections, but agreed to a ceasefire last month just before the historic referendum.
The BBC's Peter Martell in the southern capital, Juba, says the fighting is another sign of the challenges the south faces in bringing its people together and improving security.
The week-long referendum vote itself passed off peacefully, but tension remains high in parts of the oil-rich area which straddles the north and south.
Sudan's President Omar al-Bashir has promised to accept the outcome of the referendum.
Southern Sudan is to become the world's newest independent state on 9 July.
Both Sudan and the South are reliant on their oil revenues, which account for 98% of South Sudan's budget. But the two countries cannot agree how to divide the oil wealth of the former united state. Some 75% of the oil lies in the South but all the pipelines run north. It is feared that disputes over oil could lead the two neighbours to return to war.
Although they were united for many years, the two Sudans were always very different. The great divide is visible even from space, as this Nasa satellite image shows. The northern states are a blanket of desert, broken only by the fertile Nile corridor. South Sudan is covered by green swathes of grassland, swamps and tropical forest.
Sudan's arid north is mainly home to Arabic-speaking Muslims. But in South Sudan there is no dominant culture. The Dinkas and the Nuers are the largest of more than 200 ethnic groups, each with its own languages and traditional beliefs, alongside Christianity and Islam.
The health inequalities in Sudan are illustrated by infant mortality rates. In South Sudan, one in 10 children die before their first birthday. Whereas in the more developed northern states, such as Gezira and White Nile, half of those children would be expected to survive.
The gulf in water resources between north and south is stark. In Khartoum, River Nile, and Gezira states, two-thirds of people have access to piped drinking water and pit latrines. In the south, boreholes and unprotected wells are the main drinking sources. More than 80% of southerners have no toilet facilities whatsoever.
Throughout the two Sudans, access to primary school education is strongly linked to household earnings. In the poorest parts of the south, less than 1% of children finish primary school. Whereas in the wealthier north, up to 50% of children complete primary level education.
Conflict and poverty are the main causes of food insecurity in both countries. In Sudan, many of the residents of war-affected Darfur and the border states of Blue Nile and South Kordofan, depend on food aid. The UN said about 2.8m people in South Sudan would require food aid in 2013. The northern states tend to be wealthier, more urbanised and less reliant on agriculture.