FBI Director Christopher Wray said Tuesday his agency believes the Covid-19 pandemic was "most likely" caused by an incident in a laboratory in Wuhan, China.

"The FBI has for quite some time now assessed that the origins of the pandemic are most likely a potential lab incident in Wuhan," Wray said in an interview with Fox News.

The comments come after a report earlier this week said the US Department of Energy had determined that a leak from a Chinese lab was the most likely cause of the Covid-19 outbreak.

However, other agencies within the American intelligence community believe the virus emerged naturally in the world.

In the interview, Wray also accused the Chinese government of trying to stall US efforts to investigate the causes of the pandemic.

"The Chinese government... has been doing its best to try to thwart and obfuscate the work here, the work that we're doing, the work that our US government and close foreign partners are doing," Wray said. "And that's unfortunate for everybody."

Chinese officials have angrily denied the claim, calling it a smear campaign against Beijing.

The scientific community sees it as crucial to determine the origins of the pandemic in order to better fight or even prevent the next one.