The United States, which has accused China of having hidden the extent of its coronavirus outbreak, has called for a "transparent and inclusive" WHO-led international investigation into the origin of the pandemic, criticising its current terms.
The US government has accused the World Health Organisation of being "China-centric" and of being its puppet, which WHO director-general Tedros Adhanom Ghebreyesus has denied.
Tedros revealed the team's composition on Tuesday, telling the WHO annual ministerial meeting: "These are very respected individuals in their areas."
Team members came from Russia, Australia, Sudan, Denmark, the Netherlands, Germany, Japan, Vietnam, the United Kingdom and the United States, he said.
The virus, known as SARS-CoV-2, is believed to have emerged in the Chinese central city of Wuhan late last year, possibly from bats at a market with live animals.
Chinese scientists are carrying out research into its origins and how it jumped the species barrier.
The WHO-led international team formed in September is to develop plans for longer-term studies building on China's findings, according to its published terms of reference.
Garrett Grigsby, of the US Department of Health and Human Services, told the WHO's assembly that member states had been informed of the investigation's terms of reference only a few days ago.
The terms were "not negotiated in a transparent way with all WHO member states" and "the investigation itself appears to be inconsistent" with its mandate, he said, without elaborating.
"Understanding the origins of COVID-19 through a transparent and inclusive investigation is what must be done to meet the mandate," Grigsby said.
The United Kingdom called for prioritising the probe, adding: "We expect the investigation and its outcomes to be grounded in robust science."
Sun Yang, of China's National Health Commission, did not mention the investigation in his speech on Tuesday but said that China supports "WHO's continued leadership role".
German Health Minister Jens Spahn, speaking for the European Union on Monday, called for "full transparency and cooperation" during all phases of the investigation.
The WHO's top emergency expert Mike Ryan said on October 30 that the WHO-led team and its Chinese counterparts had held a first virtual meeting regarding joint investigations and would deploy on the ground in time.