A month after South Korea declared it was free of bird flu threat, the disease has been identified in ducks on a poultry farm near Seoul.

The fresh case involved a strain known as H5N8, the same type of influenza that occurred last November, an agriculture ministry official told Reuters on Monday.

More than 10,000 infected birds at a farm in Icheon, 80 kilometers (50 miles) east of Seoul, have been culled, the ministry said.

The fresh bird flu scare resurfaced after Seoul resumed poultry meat exports to Hong Kong after a two-year break.

Avian influenza or bird flu is an infectious disease of birds caused by type A strains of the influenza virus. The infection can cause a wide spectrum of symptoms in birds, ranging from mild illness, which may pass unnoticed, to a rapidly fatal disease that can cause severe epidemics, according to the WHO.

The virus does not normally infect humans but there have been instances of certain highly pathogenic strains causing severe respiratory disease in humans.