HONG KONG, Sept 24 (Reuters) - Hong Kong has partially resumed poultry imports from South China a week after suspending them because of a suspected outbreak of the H5N1 bird flu virus, the government said on Monday. Hong Kong barred imports of chilled and frozen duck and geese products from the southern province of Guangdong for a week from Sept. 17 and banned chicken imports for 21 days after a suspected outbreak of H5N1 among ducks in the Panyu district of Guangdong. On Monday the government said it was lifting the restriction on ducks and geese after an investigation showed the ducklings had died because they had not been given enough time to develop immunity from the disease after being vaccinated. "The Guangdong authorities have adopted appropriate control and preventive measures and so far no abnormal death of ducks have occurred. There is no new case of avian influenza infection in farms in Guangdong province either," a government spokesman said in a statement. With the world's biggest poultry population and millions of backyard birds roaming free, China is at the centre of the fight against bird flu. Scientists fear the bird flu virus could mutate into a form that could pass easily from person to person, sparking a global pandemic. There have been 25 human cases, including 16 deaths, from the virus in China and dozens of outbreaks in birds that have led to the culling of millions of fowl.