The two main rebel groups from Sudan's Darfur region are refusing to rejoin stalled peace talks in Nigeria. They are accusing the government of failing to keep its promise to rein in its troops.
The rebel groups remain unconvinced by assurances from Sudanese negotiators that an army offensive near the Darfur town of El-Fasher has stopped.
The chief delegate for the rebel movement Justice and Equality Movement, Mohammed Ahmed Tugod, says he has received information the attacks are continuing, in violation of the existing cease-fire.
He says he does not believe several days should be given for the troops to return to their barracks. "The area where the troops are now and the place where they left is not more than 100 kilometers," he said. "If the government genuinely wants to do this they can do this in hours rather than days."
Another rebel spokesman said the government was using helicopter gunships and artillery, while pro-government militias, known as the Janjaweed, were burning villages.
Mr. Tugod says this could result in a breakdown of the negotiations.
"If they want to continue these talks and to pave the way for the continuation of this round of talks, they have to pull out, if not, that's possibly the end of this round of talks," he said.
The chief African Union mediator Sam Ibok says he is trying to find out from neutral observers what exactly the situation is on the ground.
Sudanese delegates at the talks have said the army offensive began after rebel attacks, but Wednesday they gave assurances fighting would stop so that this, the fourth round of peace talks, could resume.
Mr. Ibok says mediators are pressing for all sides to end the violence, including the rebels. "We also appealed to the movements to honor the obligations and to refrain from any further attacks against civilians or government infrastructures including in particular the police," he said. "There is a level of responsibility for both sides but I think that right now the problem we are dealing with is the action of the government on the ground."
Diplomats in Abuja say internal problems within the rebel movements and the absence of several rebel leaders also seem to indicate this round of talks could end in failure.
They began last week with hopes of reaching a comprehensive deal quickly, but instead have been marred from the start by late arrivals, logistical difficulties and even power outages in the conference hall.
The 22-month conflict in Darfur pits mainly black African rebel groups fighting for more autonomy and oil wealth against the Arab-led government in Khartoum, and Arab militias allied to it. Tens of thousands of people have been killed and hundreds of thousands of civilians displaced.