Sudan's Darfur rebels announced a boycott of peace talks, alleging a government offensive and saying a return to the negotiating table wasn't possible until the government promised to cease attacks.
"The government is currently launching an offensive in all regions of Darfur. We are suspending the talks until the situation improves and there is a clear commitment that the Sudan government will stop the offensive," said Bahar Ibrahim of the Sudan Liberation Army.
Ibrahim told reporters on Monday that he was speaking for both insurgent groups at the latest round of African Union-sponsored peace talks, held in the Nigerian capital, Abuja.
Tens of thousands have died and nearly 2 million have been driven from their home during two years of fighting. The conflict has sparked what the UN calls the worst humanitarian crisis anywhere.
African Union officials said they were confident talks could continue as planned yesterday. Government representatives were not immediately available for comment.
The African Union officials earlier said cease-fire violations are on the rise in the western Sudanese region and the fighting was poisoning the fourth round of Darfur peace talks, which got underway officially on Saturday.
Thirteen violations of an earlier cease-fire agreement were confirmed in September and 54 documented between October and this month, said Assane Ba, an African Union spokesman.
Earlier, mediators confronted the warring parties with their cease-fire report, but only the government side responded before the meeting adjourned because of a power outage that plunged the hall into darkness, Ba said of the closed-door conference.
Government negotiators ac-knowledged partaking in skirmishes, saying they were only trying to clear Darfur's roads for humanitarian aid shipments, Ba said.
Meanwhile, the British charity Save the Children suspended its operations in south Darfur on Monday after two of its aid workers were killed during a roadside ambush.
Abhakar el Tayeb, a medical assistant, and Yacoub Abdelnabi Ahmed, a mechanic, were shot while traveling in a convoy of three vehicles.
The two, who were recruited in Sudan, were part of a mobile health clinic.
The suspension will disrupt medical care and food distribution less than a week after the UN said that the aid agencies were struggling to contain the humanitarian crisis.
Save the Children called its 30 staff in south Darfur back to its regional headquarters at Nyala to review the situation. The organization hopes the suspension will be temporary, but security in the area has been getting worse.
Spokesperson Laura Conrad said the impact of the incident would be far-reaching.
"If there are places we can't go for security reasons, it will be the same for other aid agencies," she said.
The charity said its vehicles were clearly marked as belonging to Save the Children.
The Sudanese government blamed the shooting on the Sudanese Liberation Army.
It happened between Mershing and Duma, on the road linking Nyala and the main town in north Darfur, El Fasher.
Radhia Achouri, a spokeswoman for the UN in Sudan, expressed regret for the deaths but denied a report that the UN too had suspended its operations in south Darfur.
She said that some roads were no-go areas for the UN but that this was already the case before the killings.