NEW YORK  - Researchers studying a potentially more lethal, airborne version of the bird flu virus have suspended their studies because of concerns the mutant virus they have created could be used as a devastating form of bioterrorism or accidentally escape the lab.

In a letter published in the journals Nature and Science on Friday, 39 scientists defended the research as crucial to public health efforts, including surveillance programs to detect when the H5N1 influenza virus might mutate and spark a pandemic. But they are bowing to fear that has become widespread since media reports discussed the studies in December that the engineered viruses “may escape from the laboratories” — not unlike the frightful scenario in the 1971 science fiction movie “The Andromeda Strain” — or possibly be used to create a bioterror weapon.

Among the scientists who signed the letter were leaders of the two teams that have spearheaded the research, at Erasmus Medical College in the Netherlands and the University of Wisconsin, Madison, as well as influenza experts at institutions ranging from the US Centers for Disease Control and Prevention to the University of Hong Kong. The decision to suspend the research for 60 days “was totally voluntarily,” virologist Ron Fouchier of Erasmus told Reuters. The pause is meant to allow global health agencies and governments to weigh the benefits of the research and agree on ways to minimize its risk.