Vice Premier Hui Liangyu has admitted China faces a "grave" threat from bird flu as the World Health Organization expressed concern about the latest outbreak of the disease, AFP reported. Pointing out that the country was in peak season for the disease, Hui said Hu Jintao had ordered officials to go all-out to prevent the spread of the virus, and that quarantine measures and surveillance would be stepped up accordingly. The ministry of agriculture has confirmed that more than 91,000 birds were culled following the latest outbreak in a farm in a village close to the Inner Mongolian capital of Hohhot.