Donald Trump's officials are spending the final days of his presidency ramping up accusations China covered up the existence of Covid-19.
His administration claims it will release intelligence reports in days that it says contain evidence Wuhan researchers fell ill with Covid-19-like symptoms long before the world knew of the virus.
The US has so far stopped short of backing a widespread conspiracy theory that the virus leaked from the Wuhan Institute of Virology.
Beijing has repeatedly denied the theories, saying the outbreak began in the city at the end of December 2019. It has faced international criticism for frustrating attempts to investigate the origin of the pandemic.