The top negotiator for Uganda's fugitive rebel leader Joseph Kony quit on Thursday after a delay signing a final peace deal, but sources involved in the talks said he had been fired.

"I said earlier that if Kony does not appear to sign this peace agreement, I will not associate myself with him anymore," David Nyekorach-Matsanga told Reuters on the remote Sudan-Congo border. "Today, I did not see Kony and he did not appear to sign the peace agreement."

Sources involved in the talks said Kony had apparently fired the negotiator after asking mediators to clarify parts of the document Matsanga had negotiated on his behalf.

Kony, who is wanted for multiple war crimes by the International Criminal Court (ICC), did not show his face at a planned signing ceremony on the border at Ri-Kwangba on Thursday, and appeared to have left the area again when elders went to meet him.

South Sudan's Vice President Riek Machar, the chief mediator, said the LRA leader was unsure how the Ugandan government planned to use its courts and traditional reconciliation rituals to counter the ICC arrest warrants.

Kony's 22-year rebellion killed tens of thousands of people, uprooted 2 million more in northern Uganda and destabilised neighbouring parts of southern Sudan and eastern Congo.