Mr Kony wants further assurances about war crimes indictments
The deputy leader of Uganda's rebel Lord's Resistance Army leader has been killed, according to those involved in peace talks.
LRA insiders said Okot Odhiambo and eight others were killed as rebels clashed over the proposed deal.
The fighting has delayed the signing of a final peace deal, say sources at the talks in South Sudan.
The conflict between the government and rebels has lasted two decades and cost tens of thousands of lives.
Mr Odhiambo was wanted by prosecutors from the International Criminal Court in The Hague, along with his leader Joseph Kony and another commander.
It is thought Joseph Kony did not attend the planned signing ceremony for the peace agreement last week because of differences over the proposed deal.
Meanwhile, Uganda's President Yoweri Museveni has said the LRA leader is "not serious" about peace.
He made the comments in the South Sudan capital, Juba, where he met his counterpart Salva Kiir.
Both men said they remained committed to peaceful negotiations with the LRA.
The chief mediator at the talks, South Sudan's Vice-President Riek Machar, remains camped out on the Sudan-Congo border trying to make contact with Joseph Kony.
On Friday, Ugandan government negotiators left the venue in Sudan's jungle town of Ri-Kwangba, where the peace deal was due to be signed.
Internal Affairs Minister Ruhakana Rugunda said they would return if the rebel group was ready to sign.
Last week LRA negotiator David Matsanga resigned saying there was nothing more he could do to help the peace process.
A "cessation of hostilities" agreement signed between the government and rebels is due to expire this week.