A Chinese virus research institute located at the epicentre of a coronavirus outbreak has denied links to the first patient diagnosed with the disease, amid speculation about the source of the virus.
In a statement on Sunday, the Wuhan Institute of Virology denied that one of its employees was the outbreak's "patient zero".
"Recently there has been fake information about Huang Yanling, a graduate from our institute, claiming that she was patient zero in the novel coronavirus," the institute said.
It said it had verified that the claim was not true.
It said Huang was a graduate student at the institute until 2015, when she left the province and had not returned since. Huang was in good health and had not been diagnosed with disease, it added.
The disease, now known as Covid-19, has sickened some 60,000 people around the world and killed more than 1,500, most of them in Hubei province in central China.
So far, the first patient with the illness has not been publicly identified.
While Chinese researchers and officials say the coronavirus is probably linked to wild animal consumption - "mostly likely" bats, according to Wu Yuanbin, from the Ministry of Science and Technology - there have been claims that the virus is associated with a state lab in the city.
While there is no evidence to support the claims, new central government regulations covering state biotechnology laboratories have helped fan the speculation.
On Saturday, the ministry issued a directive calling for improved management of viruses by all biological labs, and for the facilities to ensure biological safety.
Chinese authorities have said the virus is believed to be from a seafood market in Wuhan, after a cluster of patients linked the market were identified in December.
But the first patient diagnosed by the virus never visited the market, according to a study published Jan 24 in The Lancet medical journal.
In the paper, the researchers, seven of whom work at Wuhan Jinyintan Hospital, said the first patient had no exposure to the market and there was also no epidemiological link between the first patient and the later cases.
The research was based on data from the first 41 patients with confirmed infections.
Daniel Lucey, an infectious disease specialist at Georgetown University in Washington, said it was possible that the virus "came into that marketplace before it came out of that marketplace", according to Science magazine.
Frustrated and angry at the authorities' response to the outbreak, some members of the public have been unwilling to accept the official line about the probable source.
Much of the speculation has been focused on the Wuhan Institute of Virology, the only laboratory to be graded Biological Security Level 4, the highest level of biosafety precautions, on the Chinese mainland. The laboratory was designed to treat infectious diseases such as Ebola.
The unverified theory of a biological leak from the institute so widely shared online that Shi Zhengli, a lead researcher at the institute on bat-related viruses, said on her social media account that she "guaranteed with her own life" that the outbreak was not related to the facility.
China did have an outbreak of severe acute respiratory syndrome, or SARS, due to a leak from a laboratory in 2004, killing one person and infecting nine others, according to state media.
Chinese authorities said that the leak was a result of negligence and five senior officials at the Chinese Centre for Disease Control and Prevention were punished.
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This article was first published in the South China Morning Post.