Hong Kong health authorities yesterday expressed concern about a previously unreported H5N1 case in Beijing in November 2003, which pre-dated the present global bird flu outbreak. The Department of Health contacted the Ministry of Health for further details about the 24-year-old man in Beijing who died of bird flu, having initially been suspected to have had Sars, five months after Beijing was declared Sars-free. The case was revealed in Thursday's issue of the New England Journal of Medicine in a letter by a team of mainland researchers, including PLA doctors, led by Zhu Qinyu of the State Laboratory of Pathogens and Biosecurity. The research letter drew international attention, all the more so after the team asked at the last minute for the report to be withdrawn from publication. 'The department will continue to follow up this case and monitor any further reports and the global situation in relation to human avian influenza infection,' the department said in reply to questions. Hong Kong's last reported cases of H5N1 were in February 2003 - a man, who died, and his son, who recovered. The man's daughter died in Fujian while the family was on holiday, and was considered a suspected H5N1 case. Experts have long suspected the family was infected in Fujian. University of Hong Kong assistant professor of microbiology Leo Poon Lit-man said: 'We know that H5N1 was found in China a long time ago and the case of this family who went to Fujian and came back [sick] meant H5N1 is there.' The WHO office in Beijing said it had yet to receive a response from the ministry to a list of questions it submitted. The letter to the journal 'does not make absolutely clear when the H5N1 confirmatory tests were carried out', said spokesman Roy Wadia. 'We would like more details as to the man's illness, the possible source of infection, whether any of his contacts were symptomatic, the exact tests carried out.' He also urged that the virus samples be shared with the international community. The New England Journal of Medicine has yet to receive any further communication from the eight mainland researchers. Karen Pedersen, the journal's manager of media relations, said: 'Once [an] article has been printed, the authors would need to retract the article if they had concerns about it. We have not yet received an explanation from the authors regarding their request to have the letter withdrawn.'