The UN is refusing to discuss what advice it received before making the decision, but three weeks ago, a gunman opened fire at the UN's FoodandAgricultureOrganisation office in Baghdad, killing two people.
The WHO has praised Turkey's efforts but another UN agency, the FoodandAgricultureOrganisation, has given a warning that bird flu could become endemic in the country.
Some 40% of official British aid goes through the UN, the World Bank and 30-odd other multilateral organisations, with agencies such as UNESCO and the FoodandAgricultureOrganisation seen as particularly feeble.