US President Donald Trump said last week his Government was trying to determine whether the virus emanated from a lab in the central Chinese city of Wuhan, where the coronavirus pandemic emerged in December.
"All available evidence suggests the virus has an animal origin and is not manipulated or constructed in a lab or somewhere else," WHO spokeswoman Fadela Chaib told a Geneva news briefing.
"It is probable, likely, that the virus is of animal origin."
It was not clear, Ms Chaib added, how the virus had jumped the species barrier to humans but there had "certainly" been an intermediate animal host.
"It most likely has its ecological reservoir in bats but how the virus came from bats to humans is still to be seen and discovered," she said.
She did not respond to a request to elaborate on whether it was possible the virus may have inadvertently escaped from a lab.
The Wuhan Institute of Virology has dismissed suggestions both that it synthesised the virus or allowed it to escape.
(Except for the headline, this story, originally published by abc.net.au has not been edited by SLM staff)