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

In a letter in the New England Journal of Medicine last Thursday, eight Chinese scientists claimed 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 heard about the new findings through the media, and got in touch with the scientists this week," said ministry spokesman Mao Qun´an.

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

The investigation´s results will be released when it is complete, but Mao could not say when that will be.

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

He was rushed to the No 309 Hospital of the PLA, but died of pneumonia without clear cause on December 3, 2003, said Roy Wadia, spokesman for the Beijing Office of the World Health Organization (WHO).

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

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 Ministry of Health to the WHO said that the scientists have done a lot research on the dead man in the past two years and have finally resolved that he had the H5N1 virus, said Wadia.

He added that more investigation is 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.

Up to now China has reported 19 human cases of bird flu, with 12 fatalities. Globally, 225 human infections have been recorded by the WHO, with 128 deaths.