The coronavirus did not originate at a seafood market in the central Chinese city of Wuhan as previously thought, scientists say.
The disease, which has claimed the lives of more than 2400 people worldwide, was instead imported from elsewhere, said researchers from Xishuangbanna Tropical Botanical Garden under the Chinese Academy of Sciences and the Chinese Institute for Brain Research.
The team found that while the virus had spread rapidly within the Huanan Seafood Wholesale Market in Wuhan, there were also two major population expanses on December 8 and January 6, suggesting the virus was introduced from outside the market.
Earlier reports by Chinese health authorities and the World Health Organisation (WHO) said the first known patient showed symptoms on December 8 and that subsequent cases had links to the seafood market.
"The crowded market then boosted SARS-CoV-2 circulation and spread it to the whole city in early December 2019," it said.
The team's analysis said it was possible the virus began spreading in early December or even as early as November.
"The study concerning whether Huanan market is the only birthplace of SARS-CoV-2 is of great significance for finding its source and determining the intermediate host so as to control the epidemic and prevent it from spreading again," the research team said.
They also noted that while China's National Centre for Disease Control and Prevention issued a level 2 emergency warning about the new coronavirus on January 6, the information was not widely shared.
"If the warning had attracted more attention, the number of cases both nationally and globally in mid-to-late January would have been reduced," the authors said.
The research comes as the number of global coronavirus cases has hit 78,979 with more than 2400 deaths.
Italy is the latest country to be hit hard by the virus with three dead and more than 150 infected.
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The spread marks Europe's biggest outbreak so far, prompting Italian authorities to issue draconian safety measures banning public gatherings.
China's leader Xi Jinping said on Sunday the new coronavirus epidemic was the communist country's largest-ever public health emergency, but other nations were also increasingly under pressure from the deadly outbreak's relentless global march.
He said the epidemic was the "largest public health emergency" since the founding of the People's Republic in 1949.
"This is a crisis for us and it is a big test," he said on Sunday in remarks carried by state television.
In a rare admission at a meeting to co-ordinate the virus fight, he added that China must learn from "obvious shortcomings exposed" during its response.
The WHO has praised Beijing for its handling of the epidemic, but China has been criticised at home for silencing early warnings from a whistleblower doctor who later died from the virus.