The agency said the report deemed it was "likely to very likely" the virus began infecting humans through an intermediary species and "possible to likely" the virus jumped directly from bats to humans.
Director of Global Health Policy and Politics Initiative at Georgetown University, Dr Matthew Kavanagh, said while the report deepened the understanding of the virus's origins, more information was needed.
"Although the closest related viruses have been found in bats, the evolutionary distance between these bat viruses and SARS-CoV-2 is estimated to be several decades, suggesting a missing link", the report reads.
The report was written by a joint worldwide team made up of 17 Chinese experts plus 17 experts from other countries, WHO, the Global Outbreak Alert and Response Network (GOARN) and the World Organization for Animal Health (OIE).
Arguments for "Although rare, laboratory accidents do happen", the report said.
While the search has become highly politicized, governments and scientists agree that deciphering the virus's creation story is key to reducing the risk of future pandemics.
As countries rush to vaccinate and stem the spread of Covid-19, the mystery at the very heart of the pandemic - how the virus that causes the disease first jumped to humans - remains unsolved.
But the investigation has not found what other animal was infected by a bat - considered the most likely original source of the virus - and then may have transmitted it to a human.
The report did not rule out transmission through frozen food, since the virus has been shown to survive on frozen food packages, and listed the theory as "possible".
It also said the role played by a seafood market where human cases were first identified was uncertain.
Chinese researchers have said outbreaks among Beijing market workers and dock workers in eastern China's Qingdao were linked to virus particles on frozen fish.
FILE - Members of the World Health Organization team including Peter Daszak, left, Ken Maeda, right, and Vladimir Dedkov, second right, prepare to leave for field visits from their hotel in Wuhan in central China's Hubei province. "The Wuhan CDC lab which moved on 2 December 2019 reported no disruptions or incidents caused by the move".
After the outbreak, explanations floated by Chinese officials and state-media have ranged from a conspiracy theory that USA soldiers imported the virus in the 2019 World Military Games in Wuhan, to the frozen food theory after a series of outbreaks linked to workers who handled frozen goods. The authors also said that the three laboratories working in Wuhan on coronaviruses and vaccines had high biosafety levels and there was no evidence of Covid spreading among workers there.
The U.S. government has questioned whether the WHO-convened experts were given enough access to reach a reliable conclusion. China, of course, has been criticized for their lack of transparency throughout the global pandemic, and the World Health Organization has been criticized as well for echoing disinformation from the Chinese government.
US Secretary of State Antony Blinken recently told CNN they have "real concerns about the methodology and the process that went into the report, including the fact that the government in Beijing apparently helped to write it".
Another theory examined in the report, which researchers dismissed as "extremely unlikely", was that the virus could have been leaked from a Chinese laboratory - a widely-disputed claim, which was promoted by former President Donald Trump without evidence.
The report recommends more testing of blood samples taken and stored before the first outbreak in December, more testing of animals from Southeast Asia, and more in-depth study of mass gatherings that could have aided the spread of the virus.
"Cold chain food is still being brought into China, Singapore, Taiwan and all other countries with a good control of the virus", Leong told AFP.