A total of 44 people in Wuhan, Hubei province, have been diagnosed with viral pneumonia as of 8 am on Friday, local health authorities said.

Of the patients, 11 were in a serious conditions and the rest remained stable, the Wuhan Health Commission said in a release, adding symptoms include fever and breathing difficulties.

Tests on the virus pathogens and the search for the cause of the infections are still underway. Common respiratory illnesses, such as flu, avian influenza and adenovirus infection have been excluded, the release said.

All the patients have been quarantined and are receiving medical treatment in hospitals in Wuhan.

A further 121 people who had close contact with the patients are under medical observation and health authorities are tracking others who had close contact, according to the commission.

Investigation shows that some of the patients are vendors at a seafood market in Wuhan. "So far, there is no clear signs of human-to-human transmission, and no medical worker has been infected," the release said.

The market has been sanitized, according to the release. Local media reported that a notice posted outside the Huanan Seafood Market said that the commission had decided to suspend the seafood market's operations to improve its environment and sanitation.

A team dispatched by the National Health Commission has arrived in Wuhan to help local authorities.