Two more people were confirmed infected with the deadly H7N9 bird flu strain that has claimed the lives of six people nationwide, local authorities said Saturday.

The two male patients, 66 and 74 years old, respectively, developed flu symptoms late last month and were diagnosed with pneumonia over the past two days, the city's health and family planning commission said in a statement.

A total of 11 people who had close contacts with the two have not shown flu symptoms.

As of Saturday, China has confirmed 18 H7N9 cases -- eight in Shanghai, six in Jiangsu, three in Zhejiang and one in Anhui, in the first known human infections of the lesser-known strain. Of all, four in Shanghai and two in Zhejiang have died.

To stem the spread of the virus, Shanghai, Zhejiang's provincial capital of Hangzhou, and Jiangsu's provincial capital of Nanjing have suspended live poultry trading.

The National Health and Family Planning Commission said on Saturday that the country's H7N9 cases were isolated and there has been no sign of human-to-human transmission.