South Sudan's President Salva Kiir has sacked two senior aides following an embarrassing situation where he appointed a dead man to serve on a panel to lead discussions on elections scheduled for December.

Steward Soroba Budia's appointment was announced in a presidential order dated 30 January, but local media pointed out that the member of the opposition United Democratic Party (UDP), had died five years ago.

It led to people mocking the appointment on social media.

Without giving reasons, an official statement said the president had sacked his press secretary, David Amour Major and the chief administrator in the Ministry of Presidential Affairs, Valentino Dhel Maluet.

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, the statement posted on the president's official Facebook account, signed by Minister of Presidential Affairs Africano Mande Gedima, said.

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 was a signatory to the 2018 peace agreement that ended the conflict in South Sudan following its independence in 2011.

Kiir has established the panel, comprising representatives of various parties, to pave the way for elections.

There are doubts about whether the election will proceed, given the ongoing conflict.

Previous elections have been postponed, and Kiir has been 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 crimes 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.