UN chief Ban Ki-moon has expressed disappointment over the failure of talks between the Sudanese government and rebels on a ceasefire in Darfur and two other conflict zones.
The talks on a cessation of hostilities in Darfur, Blue Nile and South Kordofan were held in Addis Ababa last week after three prominent rebel groups signed a roadmap brokered by African Union mediators for ending the conflicts in the three areas.
Their signing of the roadmap, which had already been signed by the Sudanese government, had raised hopes of a breakthrough after successive rounds of abortive talks.
Tens of thousands of people have been killed and millions displaced in the three regions as ethnic minority groups rebelled against President Omar al-Bashir's Arab-dominated government.
The signing of the roadmap by two Darfur rebel groups -- the Justice and Equality Movement and the Sudan Liberation Army - Minni Minnawi faction -- and the main rebel group in the other two areas -- the Sudan People's Liberation Movement - North -- prompted the renewed ceasefire talks but they again broke down.
"The secretary general is disappointed that the Sudanese parties failed to reach an agreement on a cessation of hostilities in Darfur and the two areas of Blue Nile and South Kordofan states," a UN statement released on Wednesday said.
"He reiterates that there can be no lasting alternative to a negotiated settlement and stresses that a cessation of hostilities is the first, indispensable step towards achieving this goal."
The African Union mediating panel criticised the Darfur rebels for the failure of the talks.
"The panel believes that the parties have allowed a real and critical opportunity to slip out of their hands," it said in a statement.
It blamed the JEM and SLA-Minnawi for the failure of the Darfur talks, saying the two groups had "reopened numerous issues that had previously been agreed and others which contradicted the roadmap agreement".
The panel said that the talks on Blue Nile and South Kordofan had been derailed by disagreements over the handling of humanitarian aid.
"The impasse ... has frozen the prospects for peace for the people of Darfur and the two areas," it said.
The conflicts in the border states of South Kordofan and Blue Nile erupted when South Sudan broke away in 2011.
The Darfur rebels took up arms in 2003, triggering a conflict in which at least 300,000 people have been killed and 2.5 million fled their homes, according to the UN.