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 Food and AgricultureOrganisation office in Baghdad, killing two people.
The WHO has praised Turkey's efforts but another UN agency, the Food and AgricultureOrganisation, 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 Food and AgricultureOrganisation seen as particularly feeble.