Chinese authorities discovered on Friday the first case of a new strain of bird flu in the eastern province of Fujian, signalling the spread of the virus which has killed 23 people in China, the official Xinhua news agency reported.
The flu was first detected in March. This week, the World Health Organisation called the virus, known as H7N9, "one of the most lethal", and said it is more easily transmitted than an earlier strain that has killed hundreds around the world since 2003.
Fujian's health authority said a 65-year-old man surnamed Luo had tested positive for the virus, Xinhua reported. Thirty-seven people who had been in close contact with the man had not shown symptoms of the flu.
Chinese scientists confirmed on Thursday that chickens had transmitted the flu to humans.
This week, a man in Taiwan become the first case of the flu outside mainland China. He caught the flu while travelling in China.