At a weekend meeting in Geneva ahead of the assembly world governments failed to reach a final deal on the sharing of virus research material and vaccines in case of a global flu pandemic.

The WHO is holding talks with scientists and vaccine makers about triggering large scale pandemic vaccine production and whether to halt seasonal flu production in order to free up production capacity.

Experts have also expressed concern about possible mutation of the A(H1N1) virus that could make it more resistant to antiviral drugs such as Tamiflu and Relenza, which have been stockpiled by countries to treat severe flu.

“Scientists are concerned about possible changes that could take place as the virus spreads to the southern hemisphere and encounters currently circulating human viruses, as the normal influenza season in this hemisphere begins,” WHO Director General Margaret Chan said Friday.

Coincidentally, the assembly is also due to examine the implementation of International Health Regulations, which since 2005 oblige countries such as Mexico to swiftly raise the alarm about potential international health threats.

Mexico’s ambassador to the UN agencies in Geneva, Luis Alfonso de Alba, recently said the assembly should also debate what measures were justified in dealing with outbreaks of disease.