The decision was taken after it was found the H1N1 virus was spreading in at least global two regions. Cases are on the increase in Australia, the UK, Japan and Chile, said the body.

However, WHO head Dr Margaret Chan was quick to stress that it did not mean the virus was causing more deaths or had increased in severity.

The pandemic, which originated in Mexico in April, is thought to have spread to 30,000 people, with 141 deaths so far recorded.

The WHO has not recommended that any national borders be closed or that restrictions on the movement of people and goods are currently necessary.