The International Crisis Group said Thursday the number of dead in South Sudan was nearer to 10,000 people, a huge increase from a Dec. 26 U.N. estimate that at least 1,000 perished in the conflict between President Salva Kiir and his former vice president, Riek Machar, the New York Times reported Friday.
"Given the intensity of fighting in over 30 different locations in the past three weeks, we are looking at a death toll approaching 10,000," said Casie Copeland, an analyst with the International Crisis Group.
Herve Ladsous, U.N. undersecretary for peacekeeping operations, said Thursday the death toll probably was substantially higher than the 1,000 figure reported in late December, right after the fighting began.
Fighting started in a military barracks in Juba on Dec. 15. Kiir said Machar, whom Kiir sacked during the summer, was behind a coup attempt, a charge Machar has denied.
On Thursday, a senior State Department official challenged the version of events put forward by the South Sudanese government.
"We've not seen any evidence that this was a coup attempt, but it certainly was the result of a huge political rift between Riek Machar and the president," Linda Thomas-Greenfield, assistant secretary of state for Africa, told a Senate committee Thursday.
Machar has said that the 11 senior politicians held as suspected coup plotters must be released before a cease-fire can be put in place while Kiir said the alleged plotters must stand trial for conspiracy to overthrow the government.
In a statement, National Security Adviser Susan Rice called upon Kiir and Machar to sign a cease-fire agreement, stressing that Machar, "must commit to a cessation of hostilities without precondition."
The United States, Rice said, also "is disappointed that the detainees being held by the government of South Sudan have not yet been released," urging Kiir to release the detainees and pursue cease-fire negotiations.
"It is the obligation of both President Kiir and Mr. Machar to ensure that the lives of their people and future of their young country are not further marred by continued violence and atrocities," Rice said in her statement.
Thomas-Greenfield said the humanitarian situation is degenerating daily, with more than 200,000 people displaced inside South Sudan. More than 30,000 refugees have fled to neighboring countries.
The United Nations said it has released $15 million from its humanitarian rapid response fund for relief operations in South Sudan.