Garrett Grisby of the U.S. Department of Health and Human Services griped that the criteria for WHO's China mission had not been shared with other nations. He spoke during a weeklong meeting of the U.H. health agency's member countries.

“The (terms of reference) were not negotiated in a transparent way with all WHO member states,” he said via video conference, referring to the mission's criteria. “Understanding the origins of COVID-19 through a transparent and inclusive investigation is what must be done." In recent months, a long-planned WHO-led team seeking to investigate the coronavirus' animal origins in China has stalled.

Although pandemic travel restrictions and the focus on stemming the overwhelming number of new coronavirus cases have complicated matters, some scientists worry that China has still not provided key details about what research is already ongoing.

The U.S. objections came as an independent panel commissioned by WHO to evaluate its management of the global COVID-19 response said it's considering whether the U.N. health agency has enough power and financing to stop future pandemics.

Former New Zealand Prime Minister Helen Clark, who co-chairs the panel, said the group was especially interested in establishing an accurate chronology of the very first coronavirus alerts and what responses were taken.

“The Independent Panel will do its best to shed light on what has happened, is still happening and why,” Clark said. “We are asking whether WHO has the right mandate, the right powers, the right capacities and the right financing to deliver on pandemic preparedness and response.” Critics, including President Donald Trump, have slammed WHO for allegedly “colluding” with China to hide the extent of the initial coronavirus outbreak. Earlier this year, The Associated Press reported that senior Chinese officials didn't warn the public about the pandemic threat of coronavirus for six days and that they stalled on sharing the virus' genetic sequence and other key data with WHO experts.

Clark said the panel would also review "how well the World Health Organization and the international system at large have been able to deliver on country needs and expectations.” On Monday, WHO director-general Tedros Adhanom Ghebreyesus pleaded for more funds, saying the agency's budget was the equivalent of what the world spends on tobacco every day.

Clark has shied away from criticizing WHO or member states like China for their COVID-19 efforts.

Last month, Germany and France led a call from European Union countries arguing that WHO should have more powers to independently investigate outbreaks in countries and that their funding should be boosted.

Earlier this year, the Trump administration halted U.S. funding for the WHO and vowed to pull the United States — its biggest single donor — out of the U.N. health agency by next summer. President-elect Joe Biden has said he plans to keep the United States in the organization.

The WHO meeting finishes Saturday. So far the world has seen over 50 million confirmed coronavirus cases and 1.26 million deaths, but experts say all numbers understate the pandemic's true toll. (AP)