A lab leak of the virus is also "extremely unlikely", according to a draft copy of the report, obtained by The Associated Press.
Overall, the findings are largely as expected and left many questions unanswered.
The team proposed further research in every area, except the lab leak hypothesis.
The report's release has been repeatedly delayed, raising questions about whether the Chinese side of the study was trying to skew the conclusions to prevent blame for the pandemic falling on China.
A World Health Organization official said late last week that he expected it would be ready for release "in the next few days."
The Associated Press received what appeared to be a near-final version on Monday from a Geneva-based diplomat from a WHO-member country.
It wasn't clear whether the report might still be changed before its release. The diplomat did not want to be identified because they were not authorized to release it ahead of publication.
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