Tests were under way to determine if the girl's uncle, who lived in the same house, also died of the virus. He died 10 days later after suffering the same symptoms, officials said.
Iraqi health authorities began killing domestic birds in northern Iraq, which borders Turkey, where at least 21 cases of the deadly virus have been detected. Turkey and Iraq also lie on a migratory path for numerous species of birds.
"We regretfully announce that the first case of bird flu has appeared in Iraq," Iraqi Health Minister Abdel Mutalib Mohammed told reporters in the Kurdistan city of Sulaimaniyah, 160 miles northeast of Baghdad.
Mohammed made the announcement after receiving results from the U.S. Navy Medical Research Unit laboratory in Egypt that conducted tests on the girl, who died Jan. 17.
"The results show the inflection with the deadly H5N1," he said. "We appeal to the World Health Organization to help us.'
In other recent developments:
The Iraqi girl died after contracting a severe lung infection in her village of Raniya, about 60 miles south of the Turkish border and just 15 miles west of Iran.
The prospect of a bird flu outbreak in Iraq is especially alarming because the country is gripped by armed insurgency and lacks the resources of other governments in the region. Government institutions, however, are most effective in the Kurdish-run area of the north where the girl lived.
Dick Thompson, a WHO spokesman, said that preliminary laboratory results showed that the girl did have the H5N1 strain, but that test samples are being flown to a WHO laboratory in the United Kingdom for final confirmation.
"It is always worrying to have a new case in a new country because it raises concerns among the public," Thompson said. "But we have to understand that this is just one case."
The WHO is responding to Iraqi calls for help by putting together a crisis team to send to northern Iraq to conduct tests on the areas where the virus was found as well as people in hospitals exhibiting bird flu symptoms.
Kurdistan Health Ministry official Najimuldin Hassan said 14 people have recently been admitted to local hospitals exhibiting bird flu symptoms, but just two remain in Sulaimaniyah Teaching Hospital suspected of possibly having the disease.
It could take up to three weeks to find out how the virus entered Iraq and how it will be contained, Thompson said, adding that the security situation in Iraq would not prevent doctors from going to help.
"We need to identify what the source of this child's exposure was and to conduct epidemiological tests in the field," Thompson said. "It has to be in environment somewhere and we need to identify that before going ahead in assessing control or (bird) elimination efforts," the WHO official said.
A U.N. official in Egypt, who refused to be identified because of the sensitivity of the issue, also said 30 other samples from northern Iraq are being tested for bird flu.
Kurdistan's health minister said authorities started culling domestic birds in the village where the girl lived and nearby areas.
"Today we started a campaign to kill birds in three towns, Raniya, Dukan and Qaladaza. We formed committees to do so," said Kurdistan Health Minister Mohammed Khoshnow.
Ministry official Hassan said thousands of domesticated birds are expected to be killed, but authorities were not equipped to kill migratory birds.
"We do not know how" to kill them, he said.