Man tries to catch birds suspected of contracting bird flu virus inside Arabi farms in Kaduna, Nigeria

An environmental organization says several countries are refusing to cooperate with an investigation of the deadly strain of bird flu.

Dutch-based Wetlands International is the non-governmental agency commissioned by the U.N. Food and Agriculture Organization to research H5N1 in wild birds.

Wetlands International says Iran, Nigeria, Sudan, Tunisia and Turkey have refused to grant access to researchers.

The organization says it believes the refusals are the result of concerns by those countries about the potential impact on poultry exports and tourism if the virus is found in wild birds.

Meanwhile, European Union countries are dealing with millions of dollars in lost revenue as demand for poultry products falls off sharply.  Bird flu has spread from Asia to Europe, Africa and the Mideast, killing 94 people since 2003.

Some information for this report was provided by AFP, and Reuters.