Hong Kong's third critical case of human swine flu has been detected, involving a 39-year-old woman.

She came down with flu symptoms July 9 and was treated at the centre July 12 for upper respiratory tract infection and discharged. Without improvement, she was hospitalised July 13. She was diagnosed to have a chest infection and tested negative for swine flu July 14. However her condition worsened, requiring respiratory support early this morning. She is now getting Tamiflu treatment.

The Department of Health confirmed 88 new swine flu cases today involving 43 men and 45 women aged five to 64, bringing Hong Kong's tally to 1,640.

The new cases involve a Queen Mary Hospital nurse and three men and three women aged 22 to 46 from a residential workshop for the physically and mentally disabled in Eastern District - four workshop attendees, a resident and a staff member.

The workshop was earlier reported to have a respiratory tract infection outbreak with a confirmed swine flu case affecting a 22-year-old man.