China on Friday rejected the World Health Organization's calls for a renewed probe into the origins of Covid-19, saying it supported "scientific" over "political" efforts to find out how the virus started.

Pressure is once more mounting on Beijing to consider a fresh probe into the orgins of a pandemic which has killed more than four million people and paralysed economies worldwide since it first emerged in the central Chinese city of Wuhan.

A delayed and heavily politicised vist by a WHO team of international experts went to Wuhan in January 2021 to produce a first phase report, which was written in conjunction with their Chinese counterparts. It failed to conclude how the virus began.

China has been testing residents of Wuhan for Covid-19 after a new outbreak in the city where the virus first emerged
China has been testing residents of Wuhan for Covid-19 after a new outbreak in the city where the virus first emerged AFP / STR

On Thursday the WHO urged China to share raw data from the earliest Covid-19 cases to revive its probe into the origins of the disease.

China hit back, repeating its position that the initial investigation was enough and that calls for further data were motivated by politics instead of scientific inquiry.

"We oppose political tracing ... and abandoning the joint report" issued after the WHO expert team's Wuhan visit in January, vice foreign minister Ma Zhaoxu told reporters. "We support scientific tracing."

Graphic on key questions about the origins of the global pandemic that has killed more then 2.6 million people and devastated economies around the world.
Graphic on key questions about the origins of the global pandemic that has killed more then 2.6 million people and devastated economies around the world. AFP / John SAEKI

That report said the virus jumping from bats to humans via an intermediate animal was the most probable scenario, while a leak from Wuhan's virology labs was "extremely unlikely".

Ma rejected suggestions of new lines of investigation.

"The conclusions and recommendations of WHO and China joint report were recognised by the international community and the scientific community," he said.

A firefighter wearing protective gear against the spread of Covid-19 coronavirus sprays disinfectant in a residental area in Yangzhou, in China's eastern Jiangsu province
A firefighter wearing protective gear against the spread of Covid-19 coronavirus sprays disinfectant in a residental area in Yangzhou, in China's eastern Jiangsu province AFP / STR

"Future global traceability work should and can only be further carried out on the basis of this report, rather than starting a new one."

In the face of China's reluctance to open up to outside investigators, experts are increasingly open to considering the theory that the virus might have leaked out of a lab, once dismissed as a conspiracy propagated by the US far-right.

Even WHO chief Tedros Adhanom Ghebreyesus has said that the initial probe into Wuhan's virology labs had not gone far enough, while President Joe Biden in May ordered a separate investigation into the virus origins from the US intelligence community.

A WHO call last month for the investigation's second stage to include audits of the Wuhan labs infuriated Beijing, with vice health minister Zeng Yixin saying the plan showed "disrespect for common sense and arrogance towards science".

Meanwhile, Danish scientist Peter Ben Embarek, who led the international mission to Wuhan, said a lab employee infected while taking samples in the field falls under one of the likely hypotheses as to how the virus passed from bats to humans.

He told the Danish public channel TV2 that the suspect bats were not from the Wuhan region and the only people likely to have approached them were workers from the Wuhan labs.

Ben Embarek previously acknowledged in an interview with Science magazine that "politics was always in the room with us" during the Wuhan trip, which was mired in delays after China initially stalled approval for the international researchers' entry.

Coronavirus