There is no evidence of sustained human-to-human transmission of the H7N9 virus despite small clusters of cases, World Health Organization officials said on Monday after a two-day visit to Shanghai.

China had reported a total of 105 cases by Monday. East China's Shandong province reported its first case on Monday, and two new cases were also reported in eastern Zhejiang province, according to provincial disease control departments.

"Whenever we find a virus in animals, people become worried about whether it can be transmitted to humans. That's why domestic and international experts now pay great attention to the new strain of H7N9 bird flu," Keiji Fukuda, assistant director-general for health security and environment of the World Health Organization, said at a news conference.