The U.S. intelligence agencies have stated in a report released on Friday that the debate over whether a Chinese laboratory incident was the source of COVID-19 cannot be resolved unless China provides more information.
The report concluded that analysts would not be able to provide "a more definitive explanation" without new information from China, such as clinical samples and epidemiological data about the earliest cases.
President Joe Biden, who ordered the investigation, said Washington and its allies will continue to press China for answers.
"Critical information about the origins of this pandemic exists in the People's Republic of China, yet from the beginning, government officials in China have worked to prevent international investigators and members of the global public health community from accessing it," Biden said in a statement after the summary was released.
"The world deserves answers, and I will not rest until we get them," he added.
Also read: WHO urges China to facilitate study into origins of COVID-19 at Wuhan
The pandemic, which has claimed nearly 4.5 million lives around the world, was first triggered from the Chinese city of Wuhan in December 2019.
The report from the Office of the Director of National Intelligence said the US intelligence community remains divided on the most likely origin of Covid-19.
"All agencies assess that two hypotheses are plausible: natural exposure to an infected animal and a laboratory-associated incident."
The report is likely to worsen the already tense relations between the US and China.
China's embassy in Washington issued a statement saying the report "wrongly claimed that China continued to hinder the investigation… A report fabricated by the U.S. intelligence community is not scientifically credible."
"The origin-tracing is a matter of science; it should and can only be left to scientists, not intelligence experts," it said.
China has opposed a theory that coronavirus escaped from a lab in Wuhan. It has in fact hit back with its own purported theories including that it slipped out of a lab at the U.S. Army's Fort Detrick base in Maryland in 2019.
Several organizations within the huge U.S. intelligence community thought the novel coronavirus emerged from "natural exposure to an animal infected with it or a close progenitor virus," according to the new report.
But they had only "low confidence" in that conclusion, it said. Other groups were not able to come to any firm opinion at all on the origins.
One intelligence community segment, however, developed "moderate confidence" the first human infection with COVID-19 was likely due to a "laboratory-associated incident, probably involving experimentation, animal handling, or sampling by the Wuhan Institute of Virology."
Initially, U.S. intelligence agencies strongly favoured the explanation that the virus originated in nature. But people familiar with intelligence reporting have said there has been little corroboration over recent months that the virus had spread widely and naturally among wild animals.
