The United States intelligence agencies have found no direct evidence that Covid-19 broke out from a Chinese laboratory, a declassified report has said.
The Office of the Director of National Intelligence (ODNI) said both a natural and laboratory origin remain plausible scenarios.
It noted most US intelligence agencies agree the virus was not genetically engineered or "laboratory-adapted".
The origins of the pandemic have been a matter of bitter debate in the US.
The ODNI report was released on Friday night after Congress passed a bill in March giving US intelligence 90 days to declassify what it knew about the Wuhan Institute of Virology (WIV).
"The Central Intelligence Agency and another agency remain unable to determine the precise origin of the Covid-19 pandemic, as both (natural and lab) hypotheses rely on significant assumptions or face challenges with conflicting reporting," said the 10-page report.
Four agencies believe the virus was transferred from animals to humans, said the findings.
