CapeNature might have to close affected bird reserves if the outbreak becomes too severe

Scientists are at odds over tests that some say could be used to make a biological weapon.

The US has asked <em>Nature</em> and <em>Science</em> to censor data on a lab-made version of bird flu that could spread more easily to humans.

The World Health Organisation declared an influenza pandemic on Thursday and advised governments to prepare for a long-term battle.