A South Sudanese civil servant and two other people travelling from a government-controlled area aboard a U.N. World Food Program helicopter were detained on Tuesday after their aircraft landed in a rebel-controlled area, officials said on Wednesday.
The World Food Program spokeswoman said the agency has "received indications that they are well and unhurt, and have been assured that we would be able to pick them up today."
Tensions in South Sudan are high as President Salva Kiir and rebel commander Riek Machar seek to finalise a deal to end a conflict that has ravaged the oil-producing state since it erupted in December 2013.
The WFP helicopter was carrying Isaiah Chol, chairman of the statistics and census commission, and two other passengers who were meant to fly from one government-controlled area to another in the Jonglei region but landed instead in a rebel-held region, government officials said.
Foreign Minister Barnaba Marial Benjamin told Reuters the two other South Sudanese men worked for a non-governmental organisation. He said the South Sudanese government was working with the United Nations to ensure the three were released.
"So far we have been promised through the office of [the South Sudanese] president and United Nations that the rebels have accepted to release the three officials," said South Sudanese army SPLA spokesman Colonel Philip Aguer.
Rebel officials could not immediately be reached for comment.