Small figurines are seen in front of displayed World Health Organization logo in this illustration taken February 11, 2022. (REUTERS/Dado Ruvic/Ilustration)

WHO Director-General Tedros Adhanom Ghebreyesus said, "I have written to and spoken with high-level Chinese leaders on multiple occasions as recently as just a few weeks ago... all hypotheses on the origins of the virus remain on the table.”

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

"I wish to be very clear that WHO has not abandoned any plans to identify the origins of the COVID-19 pandemic," Tedros said.

The US Energy 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 US agencies, along with a national intelligence panel, still think COVID-19 was likely the result of natural transmission, while two are undecided, the Journal reported.