GENEVA - The coronavirus outbreak came from bats and was probably passed to humans through another intermediary animal "host", World Health Organisation (WHO) scientists have concluded.

The team of WHO experts visited the city of Wuhan, understood to be the epicentre of the Covid-19 pandemic, to probe the origins of the virus and how it spread across the world.

Scientists believe the virus jumped from animals to humans at a "wet market" in Wuhan.

However, WHO emergencies chief Mike Ryan said on Monday that this was not necessarily the case, and that "surprises were possible".

"The fact that that fire alarm was triggered (in Wuhan) doesn't necessarily mean that that is where the disease crossed from animals to human," he said.

Speaking about the fact-finding mission, A spokesperson for the health agency said: "The team had extensive discussions with Chinese counterparts and received updates on epidemiological studies, biologic and genetic analysis and animal health research."

Two specialists in animal health and epidemiology took part in the three-week advance mission, which was tasked with laying the groundwork for a broader team investigation into the origins of coronavirus and how it jumped the species barrier.

The findings would appear to further disprove a theory put forward by Donald Trump, who has said the pathogen may have originated in a laboratory in Wuhan.

However, the president has presented no evidence for this and China has denied it.

Scientists and US intelligence agencies have said coronavirus emerged in nature.

US secretary of state Mike Pompeo claimed in May he had "enormous evidence" to back up the theory that the virus came from a laboratory.

But the WHO's emergencies chief said no evidence had been provided.

Dr Mike Ryan said: "So from our perspective, this remains speculative.

"Like any evidence-based organisation, we would be very willing to receive any information that purports to the origin of the virus."

He added: "If that data and evidence is available, then it will be for the United States government to decide whether and when it can be shared, but it is difficult for the WHO to operate in an information vacuum in that regard."