The head of the Lancet Covid-19 Commission has denied claims that he is being forced by the US government to favour the theory that the pandemic started from a laboratory leak in Wuhan . Jeffrey Sachs, a professor of economics at Columbia University in New York, is the chair of the interdisciplinary initiative backed by respected medical journal The Lancet to find solutions to the pandemic. Chinese state tabloid Global Times had asked at a foreign ministry briefing on Monday about claims that scientists on the commission were being pressured to support the theory that the novel coronavirus had leaked from a lab in Wuhan, the city in China where the first cases were reported. Ministry spokesman Wang Wenbin responded that he had “taken note of this” and said the source of the pressure was the United States government. “This once again exposes that the US, while claiming to seek science-based origin tracing, is actually engaging in political manipulation under the pretext of the epidemic,” Wang said. “Now they intend to use a sinister ploy on the international scientific community to force scientists to bow in the face of their hegemony, bullying and coercion.” However, Sachs told the South China Morning Post that this was not the case. “There is no outside pressure of any kind in the work of the Lancet Covid-19 Commission. There is of course internal debate and discussion but no outside interference whatsoever,” Sachs said. Beijing’s claims of US interference highlight the degree to which a scientific question – the origins of the pandemic – has now been co-opted into a political tussle between the two superpowers. Sachs also said he was “an outspoken critic in the US of the anti-China rhetoric in Washington in recent years”. The Columbia professor co-authored an opinion piece in April arguing that the US government was wrong to use the term “genocide” to describe alleged human rights abuses in China’s Xinjiang region . Lab leak or nature? Debate heats up on the origins of Covid-19 virus On the issue of the search for Covid-19’s origins, Sachs said his views aligned with what was being discussed in the global scientific community. “I am of the view that a natural spillover event and a research-related event are both worthy of independent and objective investigation,” he said. The lab in question, the Wuhan Institute of Virology, is the first in China equipped to handle the world’s most contagious and dangerous viruses. It is now at the centre of a theory that posits the novel coronavirus did not naturally spill over into humans from bats or any intermediate hosts. Instead, the theory claims that the coronavirus was collected directly from bat caves by researchers at the WIV, who then mishandled the virus, causing it to leak into the community and starting the world’s first Covid-19 outbreak. On March 30, a joint team of Chinese government-appointed scientists and experts selected by the World Health Organization published a report on the origins of the pandemic after they spent four weeks in Wuhan. While the report concluded that a lab leak was “extremely unlikely”, WHO director general Tedros Adhanom Ghebreyesus later said it “raised further questions” that needed more research. Two months later, US President Joe Biden announced that he had given the country’s intelligence community 90 days to collect evidence that would allow Washington to make a “definitive conclusion” on whether the pandemic originated from human contact with an infected animal or from a laboratory accident. Beijing has repeatedly rejected calls for a renewed investigation or scrutiny of the lab-leak theory, instead calling on the US to open its own biosafety labs for investigation. Two weeks before Biden’s announcement, a group of 18 prominent scientists – including virologists who had collaborated with the WIV – published a letter in the academic journal Science criticising the WHO-China study for favouring the natural origins theory and dismissing the lab-leak theory. They called for both scenarios to be taken seriously until more data was available. “A proper investigation should be transparent, objective, data-driven, inclusive of broad expertise, subject to independent oversight and responsibly managed to minimise the impact of conflicts of interest,” the scientists said in the letter.