The Ugandan army says it has killed a senior commander of the rebel Lord's Resistance Army who was sought internationally for alleged war crimes.
The LRA declared a unilateral ceasefire a week ago
A military spokesman said troops shot Raska Lukwiya, whom he described as the LRA's third in command, on Saturday.
Correspondents say his death casts further doubt on the resumption of talks to end the war, which has killed thousands and displaced two million.
The talks had been adjourned until Monday amid disagreement on a truce.
Raska Lukwiya was killed in a confrontation in the northern district of Kitgum, Ugandan officials said.
Mr Lukwiya and his group of fighters had staged an ambush on Friday, killing a soldier and a civilian, they said.
"So yesterday morning we deployed our units to pursue him and Lukwiya was killed in the process," army spokesman Chris Magezi told the French news agency, AFP.
Mr Lukwiya was among five top members of the LRA, including the group's leader Joseph Kony, who are sought by the International Criminal Court to face charges including murder, rape and forcibly enlisting children.
The LRA has abducted thousands of children and forced them to fight since the conflict in the north began two decades ago.
Peace talks between government negotiators and LRA representatives in neighbouring Sudan were postponed at the weekend after the two sides failed to agree on an end to hostilities.
The Ugandan President, Yoweri Museveni, has set a 12 September deadline for thrashing out a final peace deal.
The LRA declared a unilateral truce last week but then refused to attend more talks until the government followed suit.
The government has called for a comprehensive ceasefire, which includes a demand for the rebels to provide details of their forces and deployment.
The government also wants a guarantee the LRA will not use the halt in fighting to reinforce its positions.
The talks, brokered by the government of south Sudan, had been considered the best chance of ending the 20-year-war in northern Uganda.
The LRA delegation at the talks in Juba said they were consulting with their leaders in the wake of the death of Mr Lukwiya, who they said was not the rebels' third in command.
They would issue a statement later on Sunday, they said.
The head of the Ugandan government delegation, Interior Minister Ruhakana Rugunda, said he still hoped for a quick end to the conflict.
"We regret the loss of any Uganda at this critical time when we are making every effort to end the conflict," Mr Rugunda said.