A group of scientists are proposing to conduct controversial experiments on the new H7N9 bird flu virus that may involve creating more potent strains to examine how they might spread among humans.
Professor Malik Peiris, head of virology at the University of Hong Kong, said the experiments were needed to achieve a more complete understanding of the virus or else scientists would be "working like they have one hand tied behind their back".
Critics worry about the danger of laboratory accidents and whether publishing findings from the research could offer a blueprint for bioterrorists.
Scientists who proposed the work explained, in a letter published in the journals Science and Nature, that researchers would be subject to review by biosafety committees and that high-standard risk mitigation plans would be applied.
The 22 scientists, from the US, the Netherlands, the UK and Hong Kong aim to develop more effective vaccines for H7N9 and identify mutations that lead to drug resistance. They hope to find out what makes the bird virus better adapted to mammals, more transmissible, and more able to cause diseases.
With much of the previous work on the virus done in Hong Kong and with all H7N9 human cases in China, Peiris said: "If Hong Kong is excluded, that would be very unwise."