Fighting is continuing unabated in South Sudan as the two sides prepare to begin peace talks in Ethiopia.
A South Sudanese army spokesman told the BBC that clashes are continuing in Bor and parts of Unity state.
Both the government and rebels have sent negotiating teams to the Ethiopian capital. So far the rebels have refused to end hostilities ahead of the talks.
Aid agencies say supplies are urgently needed for the many thousands of people forced to flee their homes.
Conditions have deteriorated in Awerial refugee camp on the banks of the Nile - now home to some 75,000 people who have fled the fighting in nearby Bor, the capital of Jonglei state, now in rebel hands.
"There is no clean drinking water. Five boreholes - it's just not enough," David Nash of the medical charity MSF told the BBC.
"People are drinking water straight out of the river Nile. It's muddy, it's not good. And there are no latrines, so open defecation is happening. Conditions for an outbreak of watery diarrhoea are perfect."
The bishop of Bor, Ruben Akurdit Ngong, who fled the fighting on Sunday and is now in the capital Juba, described the town as a "war zone" with "dead bodies everywhere".
"When you are in Bor town, you move around closing your nose because of the terrible smell," he told the BBC's Newsday programme.Tricky talks
Colonel Philip Aguer of the government's Sudan People's Liberation Army (SPLA), confirmed that Bor was in rebel hands.
Bor, 200km (125 miles) north of Juba, has changed hands three times in the past two weeks.
The SPLA "withdrew tactically but fighting is still going around Bor town and it is a matter of time that SPLA will restore stability to the area," the colonel told the BBC.
He also said fighting was taking place in Unity state's western Mayom area and around the oil fields in the north.
A state of emergency was declared by President Salva Kiir on Wednesday in the states of Unity and Jonglei.
At least 1,000 people have died and some 180,000 people forced from their homes since fighting erupted last month between supporters of President Kiir and those of his sacked deputy Riek Machar.
But what began as a power struggle between the two men has taken on the overtones of an ethnic conflict between members of Mr Kiir's Dinka community and the Nuer of Mr Machar.
Talks between the two sides in Addis Ababa are due to begin later on Thursday.
Observers say the discussions are likely to be complicated, as the two sides will have to agree on a mechanism to monitor a ceasefire.
Mr Kiir has already ruled out any power-sharing arrangement with Mr Machar in the longer term.
South Sudan is the world's newest state. It was formed in 2011, gaining independence from Sudan after decades of conflict.