Joseph Kony insists arrest warrants are dropped before entering negotiations
Ugandan rebels say a stalled peace process has collapsed completely after a joint attack on its positions by forces from three African countries.
Uganda, DR Congo and South Sudan launched a joint offensive on Sunday against bases of the Lord's Resistance Army (LRA) in north-eastern DR Congo.
A rebel negotiator said the offensive signalled an escalation of the war.
The Ugandan army has said that several LRA camps have been destroyed, including its main base.
Army spokesman Paddy Ankunda told the BBC that the operation had been launched because LRA leader Joseph Kony had been unwilling to end the violence in the region.
Last month Mr Kony failed to sign a peace deal, despite two years of tortuous negotiations.
The LRA has led a rebellion for more than 20 years in northern Uganda, displacing some two million people.
LRA negotiator David Nekorach Matsanga told the BBC's Network Africa programme that the involvement of troops from South Sudan - which is mediating in the conflict - meant that the peace process was now as good as dead.
He said he had not been able to contact LRA commanders since the attacks and it was not clear how much damage or casualties had been inflicted.
Mr Matsanga said he had protested to United Nations envoy at the negotiations, former Mozambican President Joaquim Chissano, saying: "We needed more time for peace. Peace was going to come. It was around the corner."
He said that Sudanese mediator Riek Machar had told him that the South Sudanese government was not aware of the attacks.
[But] "The intelligence that I have gathered is thatů a section of the SPLA [Sudan People's Liberation Army, South Sudan's army] was involved in the attack, which is a very bad precedent because it is now an escalation of the war and it puts the peace process in total collapse," he said.
Congolese Information Minister Lambert Mende Omalanga said they had decided to join in the attack out of desperation, accusing Mr Kony of being unwilling to halt his rebellion and of having attacked Congolese children.
"Or duty is to destroy terrorists and we've decided to join these neighbouring countries to do so," he told the BBC's Focus on Africa programme.
"Those people they are killing are Congolese, those children they are recruiting, those girls they are raping are Congolese kids so we have to fight for them, we have to secure them, we have to crush everybody who is coming to kill them."
BBC East Africa correspondent Peter Greste says it is doubtful that any of the three governments involved are concerned about a collapse in the peace process.
Mr Kony has repeatedly refused to sign a draft agreement and his troops have continued to attack, rape and mutilate civilians and abduct children across all three countries amidst the peace process, our correspondent says.
He is wanted by the International Criminal Court for war crimes and crimes against humanity.
Mr Kony has insisted that arrest warrants for him and for his associates must be dropped before any agreement is signed.
A statement announcing the joint operation was released in the Ugandan capital Kampala by intelligence chiefs of all three armed forces.
The statement said the attack targeted the "terrorists" at their bases in the forested area of Garamba, in the east of DR Congo.
"The three armed forces successfully attacked the main body and destroyed the main camp of Kony, code-named camp Swahili, setting it on fire," the statement said.