International experts fear that bird flu is mutating into a strain that will cause a worldwide pandemic, killing many millions of people after the mass deaths of wild birds in China.
Unconfirmed reports say that more than 100 people have also died, suggesting that the virus may have evolved to pass from person to person, breaking the final barrier preventing a worldwide catastrophe.
The Chinese government, while denying the reports of human deaths, has adopted emergency measures in Xinjiang, its remote north-western province, and has sealed off affected areas with roadblocks and closed all nature reserves.
“We are worried,” says Noureddin Mona, of the UN Food and Agriculture Organisation’s representatives in Beijing. “We should be prepared for the worst.”