Asian countries that declare victory over avian influenza should base such statements on in-depth investigations, the UN’s Food and Agriculture Organisation and the World Organisation for Animal Health (OIE) urged in a joint statement today.

The two organisations offered to provide international experts to assess the epidemiological situation.

“Collaboration between countries and the international community is essential to ensure that the avian influenza virus really is under control and that effective preventive and control measures have been put in place in each affected country and its neighbours,” the FAO and OIE said.

“The crisis is still not over,” the groups warned. “In countries such as Indonesia, Laos, Cambodia and Thailand, further outbreaks could still flare up. The virus could spread again within and between countries. As long as the H5N1 virus is not fully under control, the potential threat to human health remains.”

The statement came as South Korea confirmed its first bird flu cases for six weeks, dampening hopes the country had beaten the virus, reported the Associate Press. Officials said 400,000 chickens and ducks would be culled as a result of the latest outbreak at a chicken farm in Yangju, just north of Seoul.

Meanwhile Vietnam reported another human death from the disease, a 12-year-old boy from the southern Tay Ninh province who died on 15 March. The case has yet to be confirmed by the World Health Organisation (WHO).

“If confirmed, it does raise concerns about the continued presence of avian influenza in the poultry population,” WHO epidemiologist Peter Horby was quoted by AP as saying.

If the case is confirmed it would bring the total number of people killed by the bird flu outbreaks in Vietnam to 16. Eight people have died from the disease in Thailand.