The internet had a disruptive impact on the handling of the flu pandemic by fuelling speculation and rumours, officials said as a world health probe examined communications on swine flu yesterday.

World Health Organisation influenza chief Keiji Fukuda told a panel of 29 health experts that the internet had added a new dimension to public health alerts that became evident over the past year.

While it meant information about swine flu became more widely available, it also produced "news, rumours, a great deal of speculation and criticism in multiple outlets," including blogs, social networking and websites, he said.

"Anti-vaccine messaging was very active, made it very difficult for public health services in many countries," Ms Fukuda said as part of a nine-month review of the international response to the A(H1N1) flu pandemic.

Several governments have been trying to cancel orders for hundreds of millions of dollars' worth of special swine flu vaccines ordered last year.

Mass vaccination campaigns in Europe fell flat amid public doubts about the value of immunisation because of the milder than expected symptoms, speculation about the safety of the vaccine and concern about the influence of the pharmaceutical industry.

Former WHO infectious diseases chief David Heymann said that the public health community had to take into account the internet and social networking as a "new factor" especially amid public fears about vaccine safety in general.

"It's very difficult to correct any misperception," said Mr Heymann, now chairman of the Health Protection Agency in Britain, highlighting a contrast with traditional media.