Hong Kong's human swine flu tally has reached 104 with 12 new cases conformed, the Centre for Health Protection said on Monday.

Of the new cases, four patients - a 15-year-old girl, a 10-month-old baby girl and two boys aged six and eight - are regarded as local sporadic cases, as they had no travel history nor apparent links or contacts with any confirmed cases.

The remaining six cases are imported - two from Thailand, two from the US and two from Canada. Another case involves a younger brother of a case imported earlier from Thailand.

The 15-year-old girl is a Form Four student in Tang Shiu Kin Victoria Government Secondary School in Wan Chai. She became ill on June 12, but sat for a school internal examination with about 200 students on the same day. The school would suspend classes from tomorrow until June 29.

Centre Controller Thomas Tsang said whether a suspension of all secondary schools is required will depend on the centre's investigation of the 15-year-old case tonight, including whether there are other students who are ill with flu, too.

He noted the confirmation of flu among the two young boys shows the class suspension since June 12 is timely, as there could have been a wider disease spread.

Believing the virus has been established in different districts, including the New Territories, he expected a daily double-digit growth will continue and more cases will come up in the next one to two weeks.

Dr Tsang said the health authorities will put less emphasis on contact tracing and comprehensive surveillance in view of the community transmission. They will monitor the patronage of the designated flu clinics and see if more are needed.

The 104 cases involve 40 men and 64 women, aged 10 months to 56. About three-fourths were imported, including from the US and Canada in the initial stage, and Europe, Southeast Asia and the Philippines, South Korea and Australia afterwards.

Most cases were mild with fever, cough and runny nose, similar to the situation of a seasonal flu. The patients recovered after several days, and none required intensive care treatment or developed lung infections. There have been no fatal cases.