The WHO chief declared on Thursday it has raised flu alert level to phase 6, formally declaring that the widely spreading A/H1N1 influenza has developed into a pandemic. 'On the basis of available evidence, the scientific criteria for an influenza pandemic has been met. I have therefore decided to raise the level of pandemic alert from phase 5 to phase 6, the world is now at the start of the pandemic,' Margaret Chan told a news briefing in Geneva. 