Kiir was "pleased" to announce that the two had been relieved of their duties, and wished to express his "profound gratitude" to them for their service, said the statement posted on the president's official Facebook account, and signed by Minister of Presidential Affairs Africano Mande Gedima.

On Monday, Amour said in a press release that the president's office had relied entirely on the "accuracy and currency" of the names submitted by "stakeholders" for inclusion on the panel.

"It is now evident that a thorough verification was not done by one of the stakeholders which resulted in this unfortunate administrative oversight," Amour said.

He did not name the stakeholder, while the UDP has not commented.

It is unclear whether the statement led to Amour's dismissal. There had been speculation before the statement that he would be sacked.

Budia had been a signatory to a peace agreement signed in 2018 to end conflict that had hit South Sudan after its independence in 2011.

Kiir has set up the panel, made up of representatives of different parties, to pave the way for elections.

But there are doubts as to whether the election will take place, as the country is still experiencing conflict.

Previous elections have been postponed, with Kiir in office since independence.

The UN says more than 180,000 people are believed to have been forced to flee their homes by recent fighting.

Jonglei state is seeing the worst of it with the army battling forces aligned to South Sudan's suspended Vice-President Riek Machar.

He is currently under house arrest and on trial for murder, treason and crime against humanity. He denies the charges.

Kiir and Machar are supposed to be part of a unity government agreed in the 2018 settlement after a five-year war that followed a power struggle between the two men.