The Chief of Lancet Covid-19 Commission has dismissed claims by the Chinese government that he is being pushed by the US government to favour the Wuhan lab-leak theory, the media reported on Tuesday.

There is “no outside interference whatsoever”, Jeffrey Sachs, a professor of economics at Columbia University in New York, was quoted as saying by the South China Morning Post.

Sachs is also the chair of the interdisciplinary initiative backed by the medical journal The Lancet to find solutions to the pandemic.

His comment follows an accusation by Chinese Foreign Ministry spokesman Wang Wenbin on Monday that “some international scientists on Covid-19 origin studies, including US members of the Lancet Covid-19 Commission, were threatened, cyber attacked and forced by some US politicians to give up the widely proven natural origins hypothesis and turn to the lab-leak theory”, The Global Times reported.

Wenbin said that the US “is actually engaging in political manipulation”. However, Sachs has denied the claim.

“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 told the South China Morning Post.

He added that his views align with what’s being discussed in the scientific community about probes into Covid-19’s origins.

“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.

Earlier dismissed as a conspiracy theory, the theory that coronavirus could have leaked from the Wuhan Institute of Virology has gained fresh momentum. There have been calls for a renewed investigation both by governments and the scientific community worldwide.

US President Joe Biden has also recently ordered the intelligence community to re-double efforts to examine how the virus originated, including the lab accident theory.

China has, however, dismissed the Wuhan lab-leak theory as “extremely impossible” and has accused the US of “political manipulation”.