BEIJING - Six new human H7N9 cases have been reported in China on Friday, including one death, as more live poultry markets were shut down.

One new case, ?a 75-year-old woman from Nanjing, the capital of East China's Jiangsu province, is in a critical condition.

This brings the number of infections in the province to eight this year.

Another five new cases are all from the southern province of Guangdong, including a 67-year-old woman, who was found dead on Wednesday. Another H7N9 patient in Guangdong died on Thursday.

H7N9 has so far killed 21 in China this year, and the total number of human infections has reached 102.

With bird flu cases increasing on a daily basis, public concern over ?people-to-people transmission of the disease during Spring Festival is growing.

Li Lanjuan, researcher at the Chinese Academy of Engineering and a specialist in H7N9 prevention, said so far there have not been any cases in which one person transmits the flu to another, and the latter transmits the virus to a third person.

Her team has identified H7N9 virus mutations this year, but the mutations are not large-scale.

"Inter-human transmission is very unlikely," said Li, who added that the virus has not yet evolved to be extensively drug resistant.

The National Health and Family Planning Commission said on Wednesday live poultry markets should close if any case of H7N9 avian flu is detected.

The southern metropolis of Shenzhen has closed all live poultry markets until February 13 for a thorough cleaning. The city near Hong Kong has reported 14 human H7N9 cases since December 18.

Live poultry trading has been halted in Hangzhou, Ningbo and Jinhua cities in Zhejiang, which reported the largest number of human H7N9 cases.