The United States Wednesday called on the Sudanese government to end the forced relocation of refugees from camps in the troubled Darfur region. U.S. officials are also questioning the commitment of both the Khartoum government and Darfur rebels to African Union peace efforts.

The call for an end to the refugee relocations was the second by the State Department in as many days and reflects growing concern among both U.S. and United Nations officials that Darfur violence is again on the increase.

Sudanese forces are reported to have surrounded several refugee camps in Darfur Tuesday and forced hundreds of refugees to relocate to other sites. Sudan contends they were moved to allow better access to humanitarian aid.

However, the State Department, expressing deep concern about the reported activity, says it directly contravenes two U.N. Security Council resolutions and Sudanese obligations under U.N. guidelines for treatment of displaced persons.

Spokesman Richard Boucher called on Sudan to immediately return the refugees to the camps at El Geer in southern Darfur, to remove forces surrounding the camps, and give aid workers immediate access to the area.

Mr. Boucher said the United States stands with the international community in holding the Khartoum government responsible for the violations. He also faulted both the government, and Darfur rebels, for threats to civilians in Darfur he said call into question their commitment to regional peace efforts:

"There's been a recent kidnapping of 18 people by Darfur rebels that we find very disturbing, and in addition we've seen the mobilization of thousands of Arab militia in areas of west and south Darfur," he said. "Both indicate the parties are not really serious about establishing peace, and we call on all the parties to refrain from the acts of violence as called for in the April cease-fire agreement."

Mr. Boucher urged the sides to rapidly conclude security and humanitarian agreements at African Union-mediated talks in the Nigerian capital, Abuja.

Some 70,000 people have died and a million and a half people displaced by the Darfur conflict, pitting local rebels against Arab militiamen armed and supported by the Sudanese military.

The United States is continuing an airlift into Darfur of an African Union protection force for A.U. monitors trying to implement the April cease-fire accord reached in Chad.

Mr. Boucher said U.S. planes have so far brought in 47 Nigerian and 238 Rwandan soldiers, the vanguard of a force of some 35-hundred troops.