NANJING - Ten dead sparrows that were discovered in the city of Nanjing in East China's Jiangsu province were not infected with the deadly H7N9 bird flu strain, local authorities confirmed on Sunday.

The sparrows, which were discovered Friday in a residential compound in the city's Jianye District, all tested negative for the H7N9 virus, according to an examination from the Jiangsu Provincial Animal Health Inspection Center.

The cause of the sparrows' deaths is not yet known.

A netizen from Nanjing posted a photo of the dead sparrows online Friday evening. The post was widely forwarded and stirred concerns regarding the possible appearance of the virus in Nanjing.

Eighteen H7N9 cases had been confirmed in China as of Saturday, with eight in Shanghai, six in Jiangsu Province, three in Zhejiang Province and one in Anhui Province. Four of the Shanghai cases and two of the Zhejiang cases have resulted in death.

The cases mark the first known human infections of the H7N9 strain.

The Nanjing municipal government ordered the suspension of all live poultry trade and the immediate closing of poultry markets on Saturday.

The city's 11 administrative districts have been required to report relevant information daily.