Primary schools, nurseries and kindergartens across the territory were shut on March 13 after scores of children came down with flu symptoms and three died from flu-related illnesses.

The school closure - the first since the Sars crisis in 2003 - sparked fears of a virulent flu outbreak.

Secretary for Education Michael Suen told a news conference that the flu viruses were found to be just 'normal viruses'.

'The most important thing now is that the flu viruses have been found not to be especially severe. They are just normal viruses,' he said, adding that the number of outbreaks had dropped and was now at a level comparable to previous peak flu seasons.

'Based on these considerations, we made the decision to resume classes. But we should not be lax about the preventive measures against influenza,' he said.

Dr Thomas Tsang, controller of the Centre for Health Protection, told reporters that experts investigating the outbreak have confirmed there was no evidence of any links to the H5N1 bird flu virus.

'They are the same viruses that are prevalent this season, the genes are the same and there is no sign to say this is a (more) vicious virus,' he explained.

'Six students had severe complications resulting from flu in the last two weeks...the figure is more or less average and it goes to prove we are not seeing (a rise in) serious admission cases because of the flu season, so we are confident we can resume classes,' Dr Tsang said.

The school closure had been effective in halting the spread of the flu virus, he added, and all schools had been thoroughly disinfected over the holidays.

Although there would likely be some 'minor outbreaks' after classes resume as the peak flu season was not yet over, the authorities would be closely monitoring the situation, he said.

The city's health officials have issued guidelines to schools on sanitary measures and the circumstances under which flu outbreaks should be reported to the government.

Additional supplies of face masks and sanitisers will be sent to schools as well.

The education secretary assured parents it was safe for children to return to classes, though he did not rule out the possibility of future school closures if the need arises.

'If influenza outbreaks are detected in individual schools, we will assess the situation... and may order the school to close temporarily if we think it is necessary,' Mr Suen said.

Hong Kong Education Policy Concern Organisation chairman Mervyn Cheung warned that the government could face more criticism if there is a repeat of the hasty manner in which it shut schools earlier.

REUTERS