The Bush administration is urging Sudan's government and the rebels battling it to cooperate with efforts to end their fighting. Violence has flared in the western region of Darfur despite promises to abide by a ceasefire.
State Department spokesman Richard Boucher says the U.S. government is disturbed by the renewed violence and blames the government and the rebels for not respecting pledges to end the fighting.
"We have seen violations and problems by both sides. Both sides have been violating the ceasefire," said Mr. Boucher.
Fresh fighting between the government and rebels was reported during the weekend. The African Union (AU), which has dispatched a peacekeeping force to Sudan, says one of its helicopters was fired on while monitoring the ceasefire in western Sudan.
Mr. Boucher says the violence is hindering humanitarian operations for tens of thousands of displaced.
"Fighting between the government of Sudan, [the] Sudan Liberation Movement and Army and Justice and Equality Movement has affected United Nations and other humanitarian relief agency operations in Darfur," he added. "We urge both sides in the strongest terms to cooperate fully with international humanitarian efforts."
Spokesman Boucher called on both sides to respect the ceasefire and move toward reaching a peaceful settlement to end the fighting altogether.
African Union mediators are trying to revive stalled peace talks between Sudanese government officials and representatives of the rebel groups. The negotiations broke down last week after the rebel groups protested a renewed army offensive. The peace talks are taking place in Abuja, Nigeria and aim to end nearly two years of bloodshed.