Last Updated: 7:10AM BST 29 May 2009

A 24-year-old woman in the southern city of Guangzhou tested positive for the virus after developing a fever a day earlier, the Health Ministry said on its website. It is believed she caught the disease from a man who visited the photo studio where she works on Monday and Tuesday.

The man — a 28-year-old Chinese-American who was having wedding photos taken with his fiancee — arrived in the capital of China’s Guangdong province on Sunday from New York, where he works at a hospital. He tested positive for the flu on Wednesday.

The case raises the risk of a wider spread of the virus throughout China, a country where basic medical care is weak.

But Zeng Guang, a top epidemiology expert with the Chinese Center of Disease Control and Prevention, said that the public should not be worried about domestic transmission of the virus.

He urged people, however, to avoid crowds and people who have high temperatures as well as to frequently wash their hands, according to a statement on the Health Ministry site.