China hit back on Wednesday at US Secretary of State Mike Pompeo over his claims that the coronavirus originated in a lab in Wuhan, saying he "doesn't have any" evidence.
Washington and Beijing have clashed repeatedly over the virus, which emerged in China late last year but has since spiralled into a global pandemic.
Conspiracy theories that the virus came from a maximum-security virology lab in Wuhan have swirled since earlier this year, but were brought into the mainstream last month by US government officials.
Pompeo said on Sunday there was "enormous evidence" to show that the new coronavirus originated in a Chinese lab.
"I think this matter should be handed to scientists and medical professionals, and not politicians who lie for their own domestic political ends," said foreign ministry spokeswoman Hua Chunying at a regular press briefing. "Mr Pompeo repeatedly spoke up but he cannot present any evidence. How can he? Because he doesn't have any."
Most scientists believe the new virus jumped from animals to humans, with suspicion around a market in Wuhan that sold wildlife for meat.
US President Donald Trump has been increasingly critical of China's management of the outbreak, saying last week he had seen evidence linking the virus to the Wuhan lab and threatening new trade tariffs against Beijing.
The US is the worst-hit country in the world, with more than 70,000 deaths.
Beijing has accused the US of trying to divert attention from its domestic handling of the outbreak.
"We urge the US to stop... shifting the focus to China," Hua said. "It should handle its domestic affairs properly first. The most important thing now is to control the US' domestic pandemic spread and think of ways to save lives."
The World Health Organization has said US claims about the origin of the virus were "speculative".
The top US epidemiologist Anthony Fauci has echoed the WHO's statement, telling National Geographic that all evidence so far "strongly indicates" a natural origin.
But countries including the US and Australia have called for an investigation into how the disease transformed into a global pandemic.
Officially, China's toll for the virus is 4,633 -- but several countries have cast doubt on whether the numbers are accurate.
China and the US had only recently soothed economic tensions, with the signing of a "phase one" trade deal in January.
But since then the world's two biggest economies have been exchanging insults and accusations.
Trump and his administration angered Beijing by repeatedly referring to "the Chinese virus" when discussing the COVID-19 outbreak.
A foreign ministry spokesman in Beijing later suggested it may have been the US military which brought the virus to Wuhan, and China has sought to distance itself from the virus.
Hua said on Wednesday that there had been "many reports" suggesting that there were coronavirus cases discovered in the US or France last year, and said that this suggests the "sources (of the virus) are very diverse."
Trump has repeatedly attacked China's lack of transparency and the alleged slowness of its initial response to the outbreak.