Scientists agreed not to publish certain details of research showing how lethal bird flu can be made contagious after a U.S. biosecurity panel asked that it be kept secret for security reasons. The study at Erasmus Medical Center in Rotterdam described the genetic changes needed to make the H5N1 avian influenza strain spread easily among ferrets and potentially people. The research is under review for publication in the journal Science. It was commissioned by the U.S. National Institutes of Health, the center said yesterday in a statement on its website. Knowing the genetic sequence of a deadly, infectious strain may enable the virus to be recreated through reverse engineering. The censorship was requested by the National Science Advisory Board for Biosecurity, which was created in the aftermath of the 2001 anthrax attacks and advises the U.S. Department of Health and Human Services. The panel called for certain data to be kept secret after determining that the risks of publishing it outweigh the benefits, the Erasmus Medical Center said. The researchers have reservations about this recommendation but will observe it, the center said in the statement.