Up to 300 people fleeing fighting in South Sudan are feared drowned after a ferry accident, an army spokesman said.
Philip Aguer told AFP the boat, which was carrying people escaping fresh clashes in Malakal, was overloaded.
He said between 200 and 300 people, including women and children, had drowned in the incident on the White Nile river.
The UN says more than 350,000 people have been displaced by the fighting between rebel forces and the South Sudanese government.
Heavy fighting has been reported in Malakal as rebel forces launched a fresh raid to seize the town, which is the state capital of oil-producing Upper Nile State.
Clashes broke out in mid-December between forces loyal to President Salva Kiir and those backing his former vice president.
The UN estimates around 1,000 people have died in the country since December 15.
The boat disaster comes as talks in Ethiopian capital Addis Ababa work towards securing a ceasefire.