A Ugandan government delegation has arrived in Sudan for peace talks with the rebel Lord's Resistance Army (LRA), which could start on Tuesday.
The LRA declared a ceasefire last week
Ugandan spokesman Robert Kabushenga told the BBC that a team of his colleagues was flying to the talks in the city of Juba in southern Sudan.
Mr Kabushenga said the LRA would also take part, and the discussions would focus on ending the 20-year conflict.
However, the LRA said it would only send civilian negotiators.
It said it would not send anyone from its fighting force.
The LRA has declared a unilateral ceasefire, starting last Friday.
But the government wants this to be part of a joint agreement and says the LRA has used previous ceasefire declarations to rearm.
"We are cautious but we would like to work that declaration in terms of an agreement that is monitorable and effective," Mr Kabushenga told the BBC Network Africa programme.
He said, however, he was confident that an overall deal could be reached before the 12 September deadline.
There had been uncertainty over whether the negotiations would proceed, as scheduled on Monday.
Last week the LRA said it would not send its most senior leaders to the peace talks because of fears for their safety.
The talks are an attempt to end two decades of conflict that have left tens of thousands of people dead and millions displaced.
Announcing the ceasefire to the BBC's Focus on Africa programme, LRA deputy leader Vincent Otti said last week: "I do hope that the government of Uganda shall reciprocate this gesture of goodwill so that the warring parties may finally find a bilateral agreement to provide a peaceful atmosphere for our people."
The southern Sudanese vice-president and head mediator, Riek Machar, had asked for the group's top leaders to take part after earlier peace talks failed.
On Thursday Mr Otti told the BBC that Juba was not safe because an International Criminal Court (ICC) warrant for the LRA leaders' arrest was still in force and Ugandan government forces were present in the town.
Ugandan President Yoweri Museveni has offered the rebels a full and guaranteed amnesty and protection as long as they renounce violence.