Jan Pronk, special representative to the U.N. secretary-general, also said he remained optimistic the conflict in western Sudan could settled by the end of the year.
He spoke to reporters after his return from Darfur, where he spent two days in talks with military and political leaders of the Sudan Liberation Army.
''The commanders are united in their desire to continue the talks in order to reach a peace agreement at the end of this year, he said.
Fighting began in February 2003 when rebels from black African tribes took up arms, complaining of discrimination and oppression by Sudan's Arab-dominated government.
The government is accused of unleashing Arab tribal militia known as the Janjaweed against civilians in a campaign of murder, rape and arson. At least 180,000 people have died -- many from hunger and disease.
In Abuja, Nigeria, in early July, the SLA and the other main Darfur rebel group signed a ''declaration of principles'' with the Sudanese government, agreeing to broad commitments, including respecting Sudan's unity and upholding democracy.
The talks were to resume on Aug. 24 but the SLA has asked for a postponement. Pronk said the group wanted to convene a conference of all SLA leaders to unify their agenda.
The talks are mediated by the African Union which sets the schedule and maintains some 5,000 peacekeepers in Darfur.
AU officials said Wednesday, however, that the organization will only be able to pay its peacekeepers for three more months without help from the international community.
While donors provided air transport, accommodation and military hardware for the force to deploy, only a fraction of the cash needed has been received to finance operations of 5,086 peacekeepers, military observers and civilian police attempting to stabilize Darfur, African Union officials said.
A senior AU official, speaking on condition of anonymity because he was not authorized to publicly discuss the financial crisis facing the peacekeeping operation, said the international community would need to act quickly.
While U.N. reports have said the situation in Darfur is stabilizing and the large-scale attacks have decreased, there are frequent incidents of looting, rapes and targeted attacks.