Tamiflu-resistant H1N1 flu does not appear to be spreading in a sustained or worrisome way, a top World Health Organisation official said on Tuesday.

"At this point we are not recommending any clinical changes to the approach in treating patients," WHO Acting Assistant Director-General Keiji Fukuda said, responding to the discovery of drug-resistant H1N1 viruses in three people — one each in Denmark, Japan and Hong Kong.

"Right now these examples of oseltamivir resistance remain sporadic cases. We do not see any evidence of widespread movement of oseltamivir resistant viruses," he said, using the generic name for Tamiflu, an anti-viral tablet made by Roche and Gilead Sciences.