All schools and kindergartens in Hong Kong have been closed following a mysterious flu outbreak that killed three children recently in the former British colony, local media reported on Thursday.

A three-year-old child is in intensive care with flu-like symptoms. Three children, aged two, three and seven, died of the mysterious virus in the past two weeks, with the most recent death of a seven-year-old boy, Law Ho-ming, reported on Tuesday.

The Hong Kong authorities have instructed a team of microbiologists to attempt to determine the reasons behind the deaths.

Medics attempted to calm down concerned parents saying that school closures would help prevent the flu from spreading. So far 184 children in 23 schools have been infected.

National media quoted some doctors as saying earlier this week that the disease could be a strain of the deadly bird flu virus, which, according to the World Health Organization, has so far killed 235 people out of 371 confirmed cases worldwide.

Although no cases of human-to-human transmission of the deadly H5N1 strain of bird flu have been reported, scientists fear the virus could mutate into a strain that could pass easily between people, causing a global pandemic.