Two people were in a critical condition in a Hong Kong hospital suffering from H1N1 flu, health officials said on Friday. The cases came a year and a half after an outbreak in the city that killed more than 80 people.

The Chinese financial center is nervous about infectious diseases, following the outbreak in 2003 of the SARS virus, which killed 300 people in the city and a further 500 around the world.

"A 21-year-old female is in a critical condition after contracting H1N1 flu", said a spokeswoman for Hong Kong's Queen Elizabeth Hospital.

The woman, from the Chinese mainland, was admitted to hospital on Jan 11 and transferred to the intensive care unit on Tuesday, the spokeswoman said, adding that she could not confirm if the woman had been infected outside the city.

Also on Tuesday, a 2-year-old girl was placed in the hospital's intensive care unit suffering from the illness, the spokeswoman said.

Hong Kong's health department confirmed on Friday that the deadly influenza strain had claimed 83 lives since an outbreak in 2009 that sparked widespread panic and also drew criticism over what some described as an official overreaction.

Authorities ordered 3 million doses of H1N1 vaccine in late 2009 - enough for almost half the city's population.

In May 2009, health authorities quarantined about 300 guests and staff members at a hotel where a Mexican national carrying the disease had briefly stayed, while education chiefs ordered all primary schools to be closed for two weeks over fears about the illness spreading in the teeming metropolis.

In July 2009, a Filipino maid became the city's first fatality from H1N1 flu.

The World Health Organization said last summer that 18,156 people had died from the virus, a year after it was declared a pandemic, but that the strain of flu had become "globally less active".