Hong Kong's government has ordered schools to step up precautions against influenza as another child came down with a mysterious respiratory infection.

The latest infection brings to 32 the number of children at the Caritas Medical Center struck by the illness, which has spooked Hong Kong because it brings back memories of the SARS epidemic, which killed 299 people in the territory in 2003.

Doctors have ruled out SARS and influenza and are carrying out more tests to find the cause of the infections. An outbreak of deadly bird flu in parts of Asia this year, which killed 32 people in Thailand and Vietnam, has added to the concern.

"More test results are expected at the end of this week," said a spokeswoman for the Health Department.

The children began falling ill earlier this month. Experts say the illness appears to be mild and that it is more likely to be caused by a virus, not bacteria.

But with the advent of cooler weather and the start of the flu season, the government ordered schools late Wednesday to refrain from keeping live birds where possible, prevent children from touching birds and to avoid organizing activities which may expose children to live birds.

It also urged parents to take the temperatures of their children and not to send them to school if they have a fever.

The infections at the Caritas Medical Center have triggered fears that Hong Kong's healthcare system may not be able to cope with another outbreak.

Lawmakers grilled health officials and managers of the Caritas Medical Center at a special legislative session on Wednesday, saying they did not take precautions soon enough to prevent the disease from spreading.