A World Health Organization investigator said on Saturday that China refused to handover raw data on early COVID-19 cases.
A WHO team probing the origins of the pandemic had requested raw patient data on 174 cases from the early phase of the outbreak in the city of Wuhan in December 2019.
But Dominic Dwyer, an Australian infectious diseases expert who is a member of the team, said only summaries were provided.
"In the ideal world, you would go through patient by patient by patient, and that's we call that a line listing// And that's standard practice for an outbreak investigation. In this situation, the Chinese gave us the results, we would like I guess to receive the raw data. But that can still come."
He said the data was especially important as only half of the cases had exposure to the Huanan seafood market where the virus was initially detected.
The White House on Saturday said they have quote "deep concerns" about the WHO COVID-19 report from China; national security adviser Jake Sullivan called on China to make available data from the earliest days of the outbreak.
He said in a statement that it is imperative the report be independent and free from "alteration by the Chinese government."
However another member of the WHO mission, zoologist Peter Daszak, described "trust and openness with my China counterparts", adding that they did get access to critical data throughout.
The WHO and the Chinese foreign minister did not immediately reply to a request for comments.
The COVID-19 probe has been plagued by delay, concerns over access and bickering between Beijing and Washington, which accused China of hiding the extent of the initial outbreak.
Beijing has previously defended its transparency and its cooperation with the WHO missions.