The US Secretary of State, Condoleezza Rice, has told the Sudanese government that there must be an immediate ceasefire in the conflict in the Darfur region.
She said innocent people were suffering and dying and the deteriorating humanitarian situation was at risk of becoming a complete disaster.
Last month, the UN agreed to a 20,000-strong peacekeeping force for Darfur, but Khartoum insists it will not allow them in.
Ms Rice said Sudan must now make a choice between co-operation or confrontation on the issue.
