A Norwegian aid agency is closing down its operations in Sudan's war-torn Darfur region, citing government interference in its work.
Some 2m people have fled their homes in Darfur
The Norwegian Refugee Council (NRC) says it is aiding some 300,000 people who have fled their homes in Darfur.
The agency says it has been suspended five times, for a total of 210 days since it started work in 2004.
Sudan's government says the scale of the problems in Darfur are being exaggerated for political reasons.
Some 200,000 people have died in Darfur and two million made homeless, with pro-government militias accused of genocide against black Africans.
"We cannot work when the authorities suspend us continuously and do not respond to our repeated requests for dialogue aimed at addressing and resolving underlying reasons for this action," said NRC Secretary-General Tomas C Archer.
"This decision has been the most difficult I have had to make as secretary general of NRC," he said.
"We are all aware that the humanitarian needs are greater than ever in south Darfur."
The NRC operates in five displacement camps running schools and helping with the distribution of food and medical supplies.
Several agencies working in Darfur have complained about government interference in their work.
Violence has increased since only on rebel Darfur group signed a peace deal with the government in May.
Last week, the United Nations accused the government of backing militias who had killed some 60 people, including 30 children.
The government dismissed the report as "lies".
The government says it is disarming the Janjaweed militia, but a BBC correspondent in Sudan says all the evidence points to the exact opposite.
African Union (AU) peacekeepers say it is very clear that government and militia are working hand in hand.
Sudan's government has always said the Janjaweed militia are bandits outside their control.
The government resists plans for the United Nations to take over the peacekeeping force from the AU.
On Thursday, US State Department spokesman Sean McCormack hinted that the United States may be happy for the AU to continue leading the peace mission but with international logistical support.
"We're taking a look at how we can address the various concerns that have come up from the Sudanese government, as well as others in the region, about the nature of this international force," he said.