Peacekeepers in Sudan's Darfur region warned on Friday of a potential humanitarian catastrophe after reports of renewed displacement of civilians by alleged air strikes and other attacks.

The African Union-UN Mission in Darfur (UNAMID) said one of its patrols trying to verify reported Sudanese Armed Forces air strikes in the troubled Shangil Tobay area of North Darfur state was denied access by the SAF on Wednesday.

It was the latest restriction of movement cited by UNAMID personnel, who have a mandate to protect civilians.

"UNAMID calls on all parties involved to keep civilians out of harm's way and to grant the mission unrestricted access and freedom of movement across Darfur," Aicha Elbasri, the UNAMID spokeswoman, said in a statement.

"The mission also warns that continued fighting could lead to a catastrophic humanitarian situation for the displaced civilians in North Darfur."

She said UNAMID received reports that people had been displaced from seven villages in the Shangil Tobay area, as a result of "a series of alleged attacks by armed groups and air strikes by SAF in the area on 12 December."

UNAMID had already expressed "grave concern" about escalating violence after fighting near Shangil Tobay in early November between government forces and "an armed group".

Elbasri said UNAMID also received reports that civilians from Hashaba and three other villages in the Tawila area, west of El Fasher, had fled "as a result of air strikes allegedly carried out by SAF and of an armed group's raid on 18 December."

It did not specify who the armed groups were.

Sudan's army spokesman, Sawarmi Khaled Saad, told AFP he would "have to check our files" about what happened on the dates mentioned by UNAMID.

"But we confirm we didn't bomb any civilians," he said. "We don't have a military operation in Darfur."

Elbasri said the arrival of newly people at camps for the internally displaced would put additional pressure on limited water, health, medical and education facilities.

There are already more than one million people in Darfur's displaced camps, nine years after ethnic rebels began an uprising against the Arab-dominated Khartoum government.

Although violence is down from its peak, villages have been razed and rebel-government fighting, banditry, inter-Arab and tribal disputes continue to afflict the region, in Sudan's far west.