In December, the U.S. government asked scientists working on a man-made version of the avian flu virus to withhold certain details of their studies out of concern terrorists might use the information to manufacture and spread the dangerous virus, causing a worldwide pandemic.

At the time of the request by the U.S. National Science Advisory Board for Biosecurity, details of the studies into the H5N1 avian influenza virus were under review for publication in the journals Science and Nature.