The World Health Organization has sent a team to Van, near the border with Iran, to find out whether the children caught bird flu through human to human transmission – signalling the start of an epidemic.

«The first working hypothesis is that the children touched, played with sick chickens and were infected that way,» said Fadela Chaib, a WHO spokeswoman. «But they are also going to try to see if we are faced with a first case of human-to-human transmission, which would be the start of a flu epidemic.»

Fears that avian flu has taken hold in Turkey are growing after evidence that the disease is infecting birds in at least three areas of the country, hundreds of miles apart.

WHO inquiry as third child diagnosed with deadly bird flu