South Sudan's military says at least 200 people trying to flee fighting in the country's north were killed when their boat sank.
Army spokesman Philip Aguer said Tuesday that the boat sank in the White Nile River, as the passengers -- most of them women and children -- fled the town of Malakal.
Rebels fighting South Sudan's government for the past month said Tuesday they had captured the town, the capital of Upper Nile state. There has been no independent confirmation of the report.
Earlier, U.N. humanitarian official Toby Lanzer reported fighting in and around Malakal, and said the number of civilians seeking protection at a local U.N. base had nearly doubled in recent days to 19,000.
The warring sides in South Sudan resumed face-to-face talks Tuesday in Ethiopia's capital, as they negotiate a possible cease-fire deal.
An agreement to halt a month of fighting has been held up by the government's refusal to release 11 political detainees, as demanded by the rebels.
Army forces loyal to President Salva Kiir are battling soldiers who back former vice president Riek Machar, who Mr. Kiir fired in July.
The United Nations said Tuesday that nearly 500,000 South Sudanese have been displaced from their homes since fighting began.
The number includes nearly 75,000 who have fled to Uganda, Sudan, Kenya and Ethiopia.
The fighting has sparked fears of a full-fledged civil war in the world's newest country, which became independent from Sudan less than three years ago.