China has been urged to be "more honest" about where the Covid-19 virus came from by the US envoy there.
His remarks come a day after US media reported that a federal agency had discovered the pandemic was most likely caused by a Wuhan laboratory leak.
The global outbreak's origin "was about science and should not be politicized," the Chinese foreign ministry retorted.
Since the United States shot down an alleged Chinese spy balloon this month, relations between Washington and Beijing have deteriorated.
At a US Chamber of Commerce event on Monday, Ambassador Nicholas Burns stated that China needs to "be more honest about what happened in Wuhan three years ago with the origin of the Covid-19 crisis.".
On Sunday, US media reported that a classified intelligence report from the US Department of Energy had reached the "low confidence" conclusion that the virus was unintentionally released by a laboratory.
The energy department had previously stated that it was unsure of the virus's origin.
With varying degrees of confidence in their findings, other US agencies have come to different conclusions. In 2021, the FBI came to the "moderate confidence" conclusion that the virus escaped from a lab.
Other research indicates that it transitioned from being an animal to a human at the Huanan seafood and wildlife market in Wuhan.
There is still no definitive answer, according to John Kirby, the national security spokesman for the White House.
When asked about the rumored conclusion of the energy department, he told reporters that "there has not been a definitive conclusion and consensus in the US government on the origins of the Covid-19 pandemic.".
The lab leak theory was once more rejected on Monday by a spokesperson for China's foreign ministry.
US investigators were urged by Mao Ning to "stop smearing China and stop politicizing origins-tracing."
