China has announced that its first human bird flu death came two years earlier than previously reported, state media has said.
China's Health Ministry has confirmed the findings
A 24-year-old man died of the virus in November 2003, Xinhua news agency said.
This could make China the first country to report a bird flu fatality in this outbreak. Previously, three deaths in Vietnam in late 2003 were the first.
China's announcement raises questions about the extent of the disease in China, and its monitoring.
The case may not have been spotted because China and other Asian countries were at the time more concerned about Severe Acute Respiratory Syndrome (Sars).
The man was tested for Sars but tested negative, according to a letter from Chinese researchers who first raised the case in a letter to a US medical journal.
The scientists, who published the letter in the New England Journal of Medicine in June, said the man became ill in November 2003 and later died.
China's Health Ministry had confirmed the findings in laboratory tests that it carried out with the World Health Organisation, Xinhua said on Tuesday.
The agency did not say who the man was or where he lived.
China had previously said that its first bird flu casualty was a poultry worker who died in November 2005.
Since the latest outbreak began in 2003, more than 130 people have died around the world, mainly in South East Asia, from the H5N1 virus.
Scientists fear that the virus could mutate into a form where it could pass easily from human to human, potentially triggering a pandemic.
China was widely criticised by the international community for initially covering up the Sars epidemic in late 2002 and early 2003.
Sars killed nearly 800 people worldwide in the months after it emerged, and experts suggested China's failure to come clean about the extent of the outbreak contributed to the spread of the disease.