The international medical aid group Médecins Sans Frontières (MSF) is closing its operations in Iraq due to escalating violence and the targeting of aid workers.
MSF, which is also known as Doctors Without Borders, said it made the decision with "a great degree of regret and sadness".
Mr Gorik Ooms, general director of the organisation in Belgium, said: "It has become impossible for MSF as an organisation to guarantee an acceptable level of security for our staff, be they foreign or Iraqi."
Koen Henckaerts, director of MSF operations in Iraq, said the Nobel Peace Prize-winning group ran three aid centres in Baghdad and was setting up a fourth in Fallujah to help people in and around the Sunni militant stronghold, 40 miles west of the capital.
He said the centres were run by 90 Iraqi nationals, backed by three expatriates based over the border in Jordan but that it had become too dangerous in Iraq for nongovernmental organisations. No evacuations were planned.
"Over the past months NGOs increasingly became the target of kidnappings," Henckaerts said.
"Due to the escalating violence in the country, MSF considers it no longer acceptable to expose its staff to the serious risks that apparently come with being associated with an international humanitarian organization," MSF said in a statement posted on its website.
CARE International closed its operations in Iraq last month following the abduction of its director there, Margaret Hassan. Two Italian aid workers - Simona Pari and Simona Torretta - were released by their kidnappers after being held for three weeks in September.
Since the August 2003 attack that killed 22 people at UN headquarters in Baghdad, many relief groups have pulled their international staff from Iraq, relying instead on local employees.
AP