HONG KONG - HONG Kong on Friday detected a strain of H1N1 flu that was resistant to Tamiflu, the main anti-viral flu drug, the health department reported on its website.

The statement said the resistant strain of influenza A (H1N1) was detected during routine tests of its sensitivity to anti-virals.

'This is the first time Tamiflu resistance in HSI virus (has been) found in Hong Kong,' a spokesman said.

The case came as the Japanese health ministry said doctors had detected the second case worldwide of a patient resistant to Tamiflu, widely used to treat the illness.

In the Hong Kong case the resistant virus was isolated from a specimen taken from a 16-year-old girl who arrived in the southern Chinese city from San Francisco last month.

She was admitted to hospital and opted not to take Tamiflu, the spokesman said, but was discharged after a week.

The strain is not resistant to the other anti-viral drug, Relenza, the health department said.

A spokesman for Swiss pharmaceuticals giant Roche, which makes Tamiflu, said the company had been informed of the case and called it 'normal'. 'It is absolutely normal,' she said, adding that '0.4 per cent of adults develop resistance' to Tamiflu.

In Japan, the health ministry said doctors in Osaka prefecture had identified a woman who was resistant to Tamiflu - the second such case, after one found in Denmark.

The Japanese woman had since been treated with Relenza and was recovering, Kyodo news agency reported on Thursday, citing the health ministry.