The aid agency Goal is withdrawing all of its remaining international staff from the Darfur region of Sudan.
Three members of staff on the ground in Darfur are to be evacuated to Khartoum.
Several GOAL vehicles have been hijacked in recent months, and a GOAL staff member was killed during a forced emergency evacuation earlier this year.
Goal says the deterioration of the security situation forced them to withdraw.
Spokesman John O'Shea says their demands for the international community to send in an international peacekeeping force to protect innocent civilians and keep the aid channels open have fallen on deaf ears.
Sudanese President Omar Hassan al-Bashir has dismissed criticism by the UN secretary-general Cofi Annan.
President Bashir said the UN was making unreasonable demands and turning a blind eye to the activities of Darfur rebels.
The UN have suggested the possibility of a UN and African Union peace force in Darfur but president Bashir will not accept it.
Tens of thousands of people have been killed in Darfur and 2.5 million people driven from their homes since early 2003.
