China has accused Boris Johnson of engaging in "groundless conjecture" after he suggested that coronavirus could have spread from people grinding up the scales of pangolins.
The prime minister speculated about the origin of COVID-19 during a speech to an environmental summit on Monday.
He said it was "the product of an imbalance in man's relationship with the natural world".
The PM continued: "Like the original plague which struck the Greeks I seem to remember in book one of the Iliad, it is a zoonotic disease.
"It originates from bats or pangolins, from the demented belief that if you grind up the scales of a pangolin you will somehow become more potent or whatever it is people believe, it originates from this collision between mankind and the natural world and we've got to stop it."
But Beijing's foreign ministry spokesman Zhao Lijian said "careful and meticulous" studies were needed to discover the origin of the coronavirus outbreak.
"Groundless conjecture or hype-up of the issue will only disrupt normal international co-operation on origin-tracing," he said.
Sky News has contacted Downing Street for a response to Beijing's criticism of the PM.
Despite coronavirus first being detected in the Chinese city of Wuhan in late 2019, a World Health Organisation team will only be allowed to visit the city for the first time on Thursday.
The organisation has voiced frustration about late delays preventing its team from travelling to China last week.
Tedros Adhanom Ghebreyesus, WHO director-general, said the scientists will focus on how the virus first jumped to people.
"Studies will begin in Wuhan to identify the potential source of infection of the early cases," Dr Tedros said.
COVID-19 has killed almost two million people around the world, according to Johns Hopkins University, with more than 90 million cases recorded.
The row between London and Beijing comes as the UK government publicly criticised China's treatment of Uighur Muslims as "barbarism" and announced new measures to stop UK companies trading with Chinese firms connected to forced labour.
Foreign Secretary Dominic Raab told the Commons that there was clear evidence of "internment camps, forced labour, arbitrary detention, political re-education and forced sterilisation, all on an industrial scale. It is truly horrific".