Nigeria has culled around 700,000 birds since the outbreak of bird flu in February this year, an official from the World Health Organization (WHO) said on Thursday.

In his presentation on "An Overview of Avian Influenza in Nigeria" at one-day workshop held in Enugu, south Nigeria, WHO National Professional Officer in Nigeria Chijioke Osakwe said the birds were culled at the cost of 560 million naira (about 4.44 million U.S. dollars).

He said the country's poultry industry had 140 million birds, with "backyard" poultry farmers accounting for 60 percent of the business.

The industry contributed 9 percent to the country's Gross Domestic Product, he said, noting that the contribution was significant in the national economy.

Quoting the World Bank's prediction of an 800-million-dollar annual loss in the global poultry sector due to the raging bird disease, Osakwe said efforts must be made by all stakeholders and the citizens to stem the spread.

He described bird flu as a virus that did not require a passport to enter any country, calling for an effective campaign to educate the citizens on the need to take precautionary measures.

The WHO official likened avian flu to the "Spanish flu" which spread across the globe in 1918/1919, killing between 20 million and 40 million people.

Osakwe warned of the grave consequences of the spread of the human strain of bird flu to Nigeria.

The workshop was organized by Nigeria's Federal Ministry of Information, the National Orientation Agency and the United Nations Children's Fund (UNICEF).