China’s foreign ministry pushed back on reports of the latest assessment earlier on Monday, calling them a smear against Beijing.

US government accusations that China is withholding data about the pathogen’s origins date back to the earliest phases of the pandemic, soon after infections began surging in the country in March 2020.

US Ambassador to China Nicholas Burns, speaking in Washington by video on Monday from Beijing, underscored the importance of China being more forthcoming about how the pandemic developed.

“If we’re going to do something to strengthen the World Health Organization, then we’re going to have to push China to be more active in it,” Burns said, “and to, of course, be more honest about what happened three years ago in Wuhan, the origin of the Covid-19 crisis.”

Speaking in an interview on NBC’s Meet the Press on Sunday, Senator Dan Sullivan, an Alaska Republican, called for public hearings in Congress regarding Covid’s origins, and accused China of trying to “shut people up”.

“I think we need to do extensive hearings,” Sullivan said in the interview. “I hope our Democratic colleagues in the Congress can support that. I know the Republicans in the House are certainly supportive of that.”

State Department spokesman Ned Price also deflected questions about differing US government agency assessments about Covid-19’s origins by blaming restrictions that Beijing has placed on efforts to investigate it.

“For more than two years now, the PRC has been blocking, from the beginning, international investigators and members of the global health community from accessing information that they need to understand the origins of Covid-19,” Price said.

“This is about the question of the origins of Covid-19, but just as importantly, if not even more importantly in some respects, it is about preparing the world to withstand and ultimately to prevent another global pandemic,” he added.

Burns said a host of other outstanding bilateral issues, including US efforts to restrict China’s access to cutting-edge semiconductor chips and other advanced technologies and increased US government engagement with Taiwan, had already put a strain on the relationship.

He added, however, that transnational issues involving both countries, including climate change, required continued bilateral engagement.

“Most Americans would say, we’ve got to be present in the relationship with China, and I feel bipartisan support from both houses in Congress,” Burns said. “It’s very important that we maintain that because China will try to divide us at home as they have tried to do in the past.

“And we’ve got to have the discipline, self-awareness and strategic clarity to stick together,” he said.

Additional reporting by Mark Magnier in New York and Orange Wang in Washington