Al Jazeera's Yvonne Ndege, reporting from the Kenyan capital Nairobi, said that there were claims that Wednesday's fighting began after south Sudanese soldiers raided an LRA food store.
"This allegation has been denied by a senior southern Sudanese diplomat in Nairobi," she said.
"It seems very unlikely to me given the fact that the southern Sudanese have been at the forefront of facilitating the peace negotiations that have been going on for two years," Ndege said.
"Given my experience with LRA fighters and the SPLA [the south Sudanese army] I would not be surprised if this attack was actually unprovoked.
|Nabanga was the site of peace talks between |
the LRA and the Ugandan government
"My sense is that it was probably an ambush by the LRA to get food, water and resources from southern Sudanese soldiers."
On Thursday, a Ugandan military spokesman said that Kampala, along with the Democratic Republic of Congo and Sudan would launch a joint offensive against the guerrillas if Joseph Kony, the LRA leader, failed to commit to the peace talks.
But David Nyekorach-Matsanga, chairman of the LRA's negotiating team, said that the LRA is "committed to peace".
"I have made contacts with Joaquim Chissano [a UN special convoy to northern Uganda and southern Sudan] and the vice-president of southern Sudan and the officials of the Uganda government to make sure we do not escalate this conflict further than it has gone," he said.
"We have negotiated a very good agreement - no other person would get better than that. We only need signatures of [Ugandan] President Museveni and Josesph Kony," he said.
Kony, who is accused of war crimes by the International Criminal Court in The Hague, in April failed to show up to sign a final deal to end more than two decades of civil war in northern Uganda.
The conflict has left tens of thousands of people dead and about two million displaced.
Security experts believe that Kony spends much of his time moving between camps in northeastern DR Congo's Garamba Forest and the Central African Republic.
The group has also used bases inside southern Sudan.
Aid workers say that his forces have raided villages and abducted hundreds of civilians in the three countries in recent months.