The report by UN chief Kofi Annan, which was published this week, said that despite government pledges to launch joint military and police patrols on highways to improve security, "lawlessness and banditry have reached dangerous levels".
It said the upsurge in violence against civilians seriously affected children, and several had been abducted or killed.
The violence also hampered the delivery of humanitarian aid, and reduced initially improved prospects for the return of internally displaced people in some areas.
The report said the UN mission in Sudan (UNMIS) continued to document cases of sexual violence against women and girls every week, particularly in western Darfur where 21 cases - nine rapes, four attempted rapes and eight assaults - were reported.
The violence also targeted the African Union mission in Sudan (AMIS), with five AMIS troops killed in a firefight with an armed group - the mission's first such deaths.
"Armed clashes and banditry in western Darfur have placed severe limitations on the movement of the humanitarian community in Geneina (western Darfur)," the report said.
"All roads out of the town are restricted for humanitarian traffic and non-essential United Nations [personnel], and some staff of international non-governmental organisations have been relocated."
The security situation was also reported to be very tense in parts of southern Darfur, with incidents of banditry occurring daily.
Annan made it clear that a political solution was "paramount" and required co-ordination between the Sudanese and the international community to pave the way for a successful conclusion to the forthcoming seventh round of peace talks in Abuja, Nigeria.
The Darfur conflict has also made
"It should be made clear to all parties that the AU-facilitated peace talks in Abuja are the only vehicle for achieving a viable solution," the report said.
In Khartoum, an AU spokesman said the seventh round of peace talks had been postponed for "logistical reasons" amid a rift between Abd al-Wahid Muhammad Nur, founder of the Sudan Liberation Movement (SLM), and Mani Arko Minawi, the head of its military wing.
The AU Peace and Security Council said divisions in the leadership of the SLM were hurting efforts to resolve the 33-month-old Darfur conflict that had claimed hundreds of thousands of lives.