4 suspected patients negative

The four cases of "pneumonia without definite cause" reported in Beijing over the past week are not due to H7N9 infection or SARS, according to the city's Center for Disease Control and Prevention.

The center ran tests on the four patients because local hospitals are on the alert for H7N9 infections, Pang Xinghuo, deputy director of the center, said on Monday.

Beijing health authorities have ordered local medical institutions to report cases of pneumonia without definite causes immediately, and tests must be conducted to determine the cause.