Now, internal documents say UN officials have ordered the peacekeepers not to operate in an area where civilians are at risk in upcoming battles, after being asked to avoid the region by the south's military.

Last month rebel troops attacked the town of Phom El-Zeraf over two days. Women and children ran for their lives — straight into a river, where many drowned or were shot to death. Some 240 people — mostly civilians — were killed.

Several hundred UN forces are stationed a 90-minute boat ride from Phom El-Zeraf. But no UN forces responded until five days later.

A month later, the south's Sudan Peoples' Liberation Army has launched a campaign to stamp out an intractable rebel movement in the southern state of Jonglei, according to internal UN documents.

The southern military has told the UN that more civilians could be put in harm's way because of the military campaign, but according to internal UN security reports, the UN mission has agreed to follow a request from the southern military to suspend operations in the contested area inside Jonglei.

In one of the UN reports, dated March 7, southern army deputy chief of staff Lt. Gen. Wilson Deng met on March 3 with the UN official responsible for activities in the area of the fighting to discuss the operations against rebel leader George Athor.

Deng warned that the operations will likely result in “large displacements and collateral damages” and requested UN support to evacuate casualties in the wake of the operations.

The southern army official then “demanded” — according to the UN report — that the UN temporarily suspend all its operations in the areas. Based largely on this information, the UN document noted, the UN declared the areas specified by the army commander as “no-go zones” for the UN In practice, that means independent aid groups will likely make the areas no-go zones as well.

The UN also declared a no-fly zone over the territory, meaning aid groups are likely to follow suit.

The head of the UN peacekeeping mission in the south denied that his mission followed orders when faced with the army's demands.

“We didn't declare a no-go zone. What the military did say is that this should be a no-fly zone area,” David Gressly said in an interview Friday. “That doesn't mean that we accepted that. There's a difference.” Gressly noted that when the security advisory on the new restrictions was circulated to aid groups and the UN community following the March 3 meeting, he personally instructed UN security officials to make clear that the new conditions set by the southern military “cannot be accepted as an absolute limitation.” The UN's instructions in the March 4 security notice, however, appear more rigid than Gressly suggested in the interview.

“No UN Operations (Land, Air, and Boat) will be carried out in the No Go Areas,” read the March 4 advisory, which detailed areas in three counties in Jonglei where the southern army instructed the UN to cease operation.

Gressly told AP that the UN mission has been working with the southern authorities to restore its ability to reach and protect civilians caught in conflict in the «no go» zones.

In the past week, the southern army announced that it had dislodged the rebel leader Athor from his bush outpost.

International security sources in Juba told AP that the army was pushing Athor east, in the direction of the Ethiopian border, which could result in new populations of civilians being affected by the fighting.

The UN mission in Sudan is mandated with intervening to protect civilians. In 2009, the Security Council voted to bolster the capabilities of the UN mission to enable peacekeepers to intervene when civilians are “under imminent threat of physical violence.”