U.S. intelligence agencies said Thursday they believe the new coronavirus was "not manmade or genetically modified" but are still examining whether the origins of the pandemic trace to contact with infected animals or an accident at a Chinese lab.

The statement from the Office of the Director of National Intelligence (ODNI), the clearinghouse for the web of U.S. spy agencies, comes as U.S. President Donald Trump and his allies have speculated about the as-yet-unproven theory that an infectious disease lab in Wuhan, the epicentre of the Chinese outbreak, was the source of the global pandemic that has killed more than 220,000 people worldwide.

In recent days, the Trump administration has sharpened its rhetoric on China, accusing the geopolitical foe and vital trading partner of failing to act swiftly enough to sound the alarm to the world about the outbreak or to stop the spread of the virus that causes COVID-19.

The new ODNI statement says, "The Intelligence Community also concurs with the wide scientific consensus that the COVID-19 virus was not manmade or genetically modified."

"The IC will continue to rigorously examine emerging information and intelligence to determine whether the outbreak began through contact with infected animals or if it was the result of an accident at a laboratory in Wuhan."

"The mere fact that we don't know the answers — that China hasn't shared the answers — I think is very, very telling," Secretary of State Mike Pompeo said recently.

Trump on Thursday took it a step further, suggesting the release could have been intentional, reflecting another occasion in which he's clashed with U.S. intelligence, which occurred most notably on the subject of Russian interference in the 2016 election.

"It's a terrible thing that happened," the president said Thursday at the White House. "Whether they made a mistake or whether it started off as a mistake and then they made another one, or did somebody do something on purpose."

Pompeo has pressed China to let outside experts into the lab "so that we can determine precisely where this virus began."

While Trump and Pompeo have made public statements speculating about the lab, a U.S. intelligence official disputed the notion that there was any pressure on agencies to bolster a particular theory. The intelligence official was not authorized to publicly discuss the issue and spoke only on condition of anonymity.

The agency has not had a Senate-confirmed director since Dan Coats stepped down last year, with Joseph Maguire and now Richard Grenell filling in on an interim basis.

Rep. John Ratcliffe of Texas, one of the Trump's most loyal defenders during the impeachment process, has been nominated to succeed Coats, with a Senate confirmation hearing tentatively scheduled for next week when the Senate reconvenes.

Scientists say the virus arose naturally in bats. Even so, Pompeo and others have pointed fingers at an institute that is run by the Chinese Academy of Sciences. It has done groundbreaking research tracing the likely origins of the SARS virus, finding new bat viruses and discovering how they could jump to people.

"We know that there is the Wuhan Institute of Virology just a handful of miles away from where the wet market was," Pompeo said two weeks ago. The institute has an address 13 kilometres from the market that is considered a possible source.

U.S. officials say the American Embassy in Beijing flagged concerns about potential safety issues at the lab in Wuhan in 2018, but they have yet to find any evidence the virus originated there nearly two years later.

The Chinese government said Thursday that any claims that the coronavirus was released from a laboratory are "unfounded and purely fabricated out of nothing."

Foreign Ministry spokesperson Geng Shuang cited the institute's director, Yuan Zhiming, as saying the lab strictly implements bio-security procedures that would prevent the release of any pathogen.

"I would like to point out again that the origin of the virus is a complex scientific issue, and it should be studied by scientists and professionals," Geng said.

Geng also criticized U.S. politicians who have suggested China should be held accountable for the global pandemic, saying they should spend their time on "better controlling the epidemic situation at home."

But a Chinese government spokesperson, Zhao Lijian, demonstrated that China was not above sowing confusion in the face of the pandemic. He tweeted in March the falsehood that the virus might have come from the U.S. Army.