Hong Kong authorities ordered all primary schools in the city to be closed for two weeks after the first cluster of local swine flu cases was found.
The move came after 12 pupils at a city secondary school were found to have contracted the A(H1N1) virus, chief executive Donald Tsang told reporters.
Tsang said authorities were unable to identify the source of the infection, making it the first "cluster" of human swine flu cases in the city without a known link to those travelling overseas.
All primary schools, kindergartens, child care centres and special schools would be shut for 14 days from Friday in an effort to control the spread of the virus, Tsang said.
"Given the global situation, (for) Hong Kong to have its own local cases is simply inevitable," Tsang said.
"I believe the fellow citizens and the government have done all we can in postponing the arrival of the first indigenous case."
The latest move came more than a month after Hong Kong officials confirmed Asia's first case of the A(H1N1) virus, sparking the week-long quarantine of around 300 guests and staff at a city hotel.
The city is very nervous about infectious diseases following the outbreak of the SARS virus in 2003, which killed 300 people here and a further 500 around the world after one carrier spread the disease in a Hong Kong hotel.
The move to shut primary schools rather than secondary schools was made because young pupils are more vulnerable to catching the virus, Tsang said.
There have been around 50 confirmed cases of human swine flu infection in Hong Kong, but all the previous cases caught the virus while travelling abroad.
Since the A(H1N1) virus was first discovered in the United States and Mexico in April, some 74 countries have reported more than 27,000 cases including 141 deaths, the World Health Organization has said.