China has reported two cases of bird flu in a new province, west of the area where the disease has been centered.
The state Xinhua news agency said that the two human cases were reported Sunday in central Henan province.
Until Saturday, when the case of a seven-year-old girl was reported in the capital, Beijing, the breakout of the H7N9 strain of bird flu had been clustered around the eastern city of Shanghai, hundreds of kilometers away.
Michael O'Leary, the head of the World Health Organization's office in China, said Sunday that the spread of the deadly virus to other parts of the country is not surprising and was expected.
Eleven people have died in eastern China since the virus was reported in humans for the first time last month. The virus is believed to have been transmitted from birds to humans, triggering massive culls at poultry farms and restrictions on poultry trade.
Experts worry that this new strain of bird flu could become easily transmissible and trigger a pandemic, although WHO says so far there is no evidence of the virus spreading from human to human.