Chinese scientists are continuing with investigations into what is believed to be the world's first bird flu human fatality.

In a letter published in the New England Journal of Medicine last Thursday, eight Chinese scientists claimed that a 24-year-old Beijing man who died in late 2003 had contracted H5N1 avian influenza.

The experts, including Cao Wuchun from the State Key Laboratory of Pathogens and Biosecurity, said the virus was isolated in a sample taken from the man.

"The Ministry of Health (MOH) heard about the new findings through the media, and got in touch with the scientists this week," ministry spokesman Mao Qun'an said.

The ministry is now organizing a retrospective investigation into the death, including further laboratory tests, epidemiology research and clinical treatment, Mao added.

The investigation's results will be released when it is completed, but Mao could not say when that would be.

The dead man, who served in the army, fell ill on November 25, 2003, the year China was hit by the severe acute respiratory syndrome (SARS) outbreak.

He was rushed to the People's Liberation Army No.309 Hospital, but died later of pneumonia on December 3, 2003, according to Roy Wadia, spokesman for the Beijing Office of the World Health Organization (WHO).

Tests at that time showed he had not died of SARS, Wadia added.

At that time, no human cases of avian influenza, or bird flu, had been reported by health authorities on the Chinese mainland. The first case was reported two years later, in November 2005.

According to WHO sources, current outbreaks of the H5N1 virus were first recognized in early 2004 in Viet Nam.

A report given by the MOH to the WHO said that the scientists had done a lot research on the dead man in the past two years and have finally resolved that he had the H5N1 virus, Wadia said.

He added that further investigations were needed.

"For example, we need to know the source of the man's infection, and we need to learn the situation of his family members or people who he had close contact with."

To date, China has reported 19 human cases of bird flu, including 12 fatalities. Globally, 225 human infections have been recorded by the WHO, including 128 deaths.

Editor: Yan