There were 27 cases of 'viral pneumonia of unknown origin, reported in Wuhan, in central Hubei province, the city's health commission said in a statement.
Authorities are investigating an outbreak of viral pneumonia in central China amid online speculation that it might be linked to SARS, the flu-like virus that killed hundreds of people a decade ago.
There were 27 cases of "viral pneumonia of unknown origin" reported in Wuhan, in central Hubei province, the city's health commission said in a statement.
Seven patients were in a critical condition, while the others were stable and two could be discharged soon, the commission said.
Initial lab tests have found that there was no "apparent human-to-human transmission" and that no medical staff were infected, the statement said.
"Investigation of the cause of infection is ongoing," it added.
All patients have been quarantined and their close contacts are under medical observation, according to the commission.
Most of the patients worked at a seafood market in the city, it said.
News of the mystery pneumonia outbreak led to speculation online that it might be linked to Severe Acute Respiratory Syndrome, a highly contagious respiratory disease.
"A number of health officials in Wuhan said that the cause of the current outbreak is not clear, and it cannot be concluded that it is the SARS virus as rumoured online," the official newspaper People's Daily said on its Weibo microblog.