A strain of influenza A/H1N1 virus was found resistant to anti-flu drug oseltamivir in Hong Kong laboratory tests, local health authorities said on Friday.

A spokesman for the Department of Health of Hong Kong said the department's Public Health Laboratory Services Branch (PHLSB) Friday detected a strain of A/H1N1 flu virus which was resistant to oseltamivir, i.e. Tamiflu.

The virus was identified during PHLSB's routine sensitivity test of the new flu virus to oseltamivir and zanamivir, the spokesman said.

Hong Kong has maintained an antiviral stockpile of both Tamifluand Relenza.

"Tests showed that this strain is sensitive to zanamivir, i.e. Relenza," he said.

He said this is the first time Tamiflu resistance in influenza A/H1N1 virus found in Hong Kong, adding that similar cases were also reported in Denmark and Japan.

The virus was isolated from the specimen taken from a 16-year- old girl coming from San Francisco. She was intercepted by Port Health Office at the Hong Kong International Airport on June 11 upon arrival.

The girl was then admitted to Queen Mary Hospital for isolation. She was tested positive to influenza A/H1N1 but opted not to take tamiflu. She had mild symptoms and was eventually discharged upon recovery on June 18.

"This is the only Tamiflu-resistant strain so far among some 200 influenza A/H1N1 samples tested in Hong Kong. Further tests are underway," the spokesman said.

He noted that PHLSB conducted routine sensitivity tests on specimens taken from confirmed A/H1N1 flu patients.

The case will be reported to the World Health Organization (WHO) , the spokesman said.

(Xinhua News Agency July 4, 2009)