At least 200 South Sudanese civilians have drowned in a ferry accident while fleeing fresh fighting between government forces and rebels.
Army spokesman Philip Aguer said the disaster happened when the overloaded boat, packed with women and children escaping the northern oil city of Malakal, capsized in the White Nile river.
"The reports we have are of between 200 to 300 people, including women and children. The boat was overloaded," he said on Tuesday.
"They all drowned. They were fleeing the fighting that broke out again in Malakal."
Aguer said the tragedy happened on Tuesday, although local media reported it occurred overnight Sunday.
The disaster is one of the worst single incidents to have been reported from the war-torn country since clashes began a month ago between rival army units loyal to President Salva Kiir and his former vice president Riek Machar.
According to the United Nations, about 400,000 civilians have fled their homes over the past month, many of them to escape a wave of ethnic violence between members of Kiir's Dinka people - the country's largest group - and Machar's Nuer community.
Up to 10,000 people are believed to have been killed in the fighting, aid sources and analysts say.
The army spokesman, meanwhile, reported that battles were raging in several areas of the country, signalling that the government's recapture of Bentiu, another key oil city in the north which fell last week, had failed to deal a knock-out blow to the rebels.
Heavy fighting was reported in Malakal, state capital of oil-producing Upper Nile state, as rebel forces staged a fresh attack to seize the town, which has already changed hands twice since the conflict began.
More than 78,000 South Sudanese have fled to neighbouring nations since fighting began in mid-December, the UN refugee agency said on Tuesday, the majority of them crowded into camps in Uganda.