China recorded three bird flu cases last year, all fatal. The bird flu virus is constantly mutating, and experts fear it could change into a form that is easily transmitted from person to person and kill millions of people worldwide.
At present, H5N1 remains mainly a bird virus, but WHO data released in mid-December showed 247 people had died from it out of 391 cases since the virus resurfaced in Asia in 2003.
"We received confirmation of the case from the Chinese health ministry. A 19-year-old woman died on Monday in Beijing of H5N1," WHO spokesman Gregory Hartl said in Geneva. He had no further information.
Earlier, the Beijing Municipal Bureau and Hong Kong's government gave more details of the latest case.
"The woman fell ill on December 24, was hospitalised on December 27 and died on Monday at 7.20 am," the bureau said in a faxed statement.
Hong Kong's Centre for Health Protection said the woman had had contact with poultry before the onset of symptoms. China's official Xinhua News Agency earlier reported the woman had bought nine ducks at a market in Hebei province, which surrounds Beijing.