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Controversial H5N1 bird flu research resumes

24 January 2013 Last updated at 00:39 GMT

Controversial research into making bird flu easier to spread in people is to resume after a year-long hiatus.

Some argue the research is essential for understanding how viruses spread and could be used to prevent deadly pandemics killing millions of people.

The study was stopped amid fierce debate including concerns about modified viruses escaping the laboratory or being used for terrorism.

Rebecca Morelle reports.