(Reuters) - Researchers studying a potentially deadlier, airborne version of the bird flu virus have voluntarily suspended their studies for 60 days because of concerns it could be used as a devastating form of bioterrorism, according to a letter published in the journals Nature and Science on Friday.

Ron Fouchier of Erasmus Medical College in the Netherlands, Adolfo Garcia-Sastre of Mount Sinai School of Medicine in New York and Yoshihiro Kawaoka of the University of Wisconsin, Madison, defend the research as crucial to public health efforts to detect when the H5N1 influenza virus might change in the wild in a way that could spark a pandemic.

But they are bowing to widespread fear that the mutant viruses "may escape from the laboratories" and be used to create a bioterror weapon, they wrote.

A U.S. advisory committee in December had asked Science and Nature to censor details of the research from two teams that was submitted for publication. Biosecurity experts fear an airborne version transmissible between humans could spark a pandemic worse than the 1918-19 outbreak of Spanish flu that killed between 20 million and 40 million people.

The studies from Erasmus and the University of Wisconsin have shown that the mutant H5N1 can be transmitted through the air between ferrets, which are considered good models of how influenza viruses behave in people.

They have not taken the next step to see whether the altered virus can be transmitted the same way between people by coughing or sneezing, because such an experiment would be unethical.

To give the scientific community and governments time to determine whether the research can be conducted safely, the scientists write, "we have agreed on a voluntary pause of 60 days on any research involving highly pathogenic avian influenza H5N1 viruses" that can produce easily transmissible forms of the virus.

The researchers wrote that no experiments with live, mutant viruses "already shown to be transmissible in ferrets will be conducted during this time."

(Reporting by Sharon Begley; Editing by Doina Chiacu and Bill Trott)

[Image via Shutterstock.com.]

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