Garang's death would be a heavy blow to the January peace deal that ended a 21-year civil war between the mostly Muslim north and the Christian and animist south in which some 2 million people died.

Thirteen others aboard the craft were also killed, an official statement said. The crash site was found near the Uganda-Sudan border, a Ugandan official said.

Ugandan officials said Garang and the others were flying in one of President Yoweri Museveni's personal helicopters, but the Sudanese statement said it was a plane. The conflict could not be immediately reconciled. Ugandan and Sudanese forces had been searching for Garang's aircraft since Sunday.

"It has now been confirmed that the plane crashed after it hit a mountain range in southern Sudan because of poor visibility and this resulted in the death of Dr. John Garang DeMabior, six of his colleagues and seven other crew members of the Ugandan presidential plane," according to a statement released by the office of Sudanese President Omar el-Bashir.

The 60-year-old former rebel, who was sworn in as vice president just three weeks ago, left on a flight from Uganda for southern Sudan at 5:30 p.m. Ugandan time Saturday afternoon, Sudanese and Ugandan officials said. It was not clear when the last contact with his craft took place.