More today.

Yesterday six more children who have tested positive for avian flu remained in a critical condition in the Turkish city of Van, near Dogubayazit. Another 24 suspected cases are being treated in a special ward in the university hospital.

A further 18 patients with symptoms of the disease, most of them children, are being treated in hospitals in the eastern cities of Yozgat, Erzurum and Diyarbakir. Other cases are being investigated.

The more the virus comes into contact with humans, the more likely it is to mutate into a form that can be transmitted between people. This has not yet happened; if it does it could start a global pandemic.

The H5N1 strain has killed half of all the people who have contracted it. The Spanish flu of 1918, which killed 40m people, was fatal in fewer than one in 10 cases.