After hearing that the U.S. Energy Department had determined that a Chinese laboratory leak was most likely to blame for the COVID-19 epidemic, the U.S. ambassador to China remarked on Monday that China needed to be more forthright about its origins.

The World Health Organization (WHO), according to Nicholas Burns, needs to push China to play a more active role if it is to be strengthened. Burns made this statement while participating in a U.S. Chamber of Commerce event via video link.

China also needed to “be more honest about what happened three years ago in Wuhan with the origin of the COVID-19 crisis,” Burns said, referring to the central Chinese city where the first human cases were reported in December 2019.

The Wall Street Journal first reported on Sunday that the U.S. Energy Department had concluded the pandemic likely arose from a Chinese laboratory leak, an assessment Beijing denies.

The department made its judgment with “low confidence” in a classified intelligence report recently provided to the White House and key members of Congress, the Journal said, citing people who had read the intelligence report.

Four other U.S. agencies, along with a national intelligence panel, still judge that COVID-19 was likely the result of natural transmission, while two are undecided, the Journal reported.

The Energy Department did not respond to a request for comment.

President Joe Biden’s national security adviser, Jake Sullivan, said on Sunday there were a “variety of views in the intelligence community” on the pandemic’s origins.

“A number of them have said they just don’t have enough information,” Sullivan told CNN.

Asked to comment on the report, which was confirmed by other U.S. media, China’s foreign ministry referred to a WHO-China report that pointed toward a natural origin for the pandemic, likely from bats, rather than a lab leak.

“Certain parties should stop rehashing the ‘lab leak’ narrative, stop smearing China and stop politicizing the origins-tracing issue,” foreign ministry spokesperson Mao Ning said.