According to Dr. Fukuda a WHO panel of experts concluded that the hypothesis does not bear scrutiny because the lysine residues and mutation rates were typical and many swine flu appear unrelated because not enough pigs are tested each year".

Dr. Fukuda says he doubts that the rumour would prove to be damaging and he would not want genetic sequences kept off public databases - however persistent false rumours such as linking childhood immunisation shots to autism, can have devastating effects on controlling diseases.

While scientists have yet to accurately pinpoint the exact origin of the new swine flu the earliest cases in Mexico were found to contain genes from flu viruses that normally circulate in pigs in Europe and Asia, as well as avian and human genes.

The H1N1 influenza virus is expected to dominate the WHO's annual 9 day conference in Geneva but will also shorten it so that the 193 health delegates can return home to deal with the looming pandemic.

According to the WHO to date the virus has spread to 33 countries, 6,497 cases have been reported and 65 people have died - 4,300 confirmed and probable cases, with 3 deaths, were reported in the United States.