US President Donald Trump has warned China that it should face consequences if it was "knowingly responsible" for the spread of COVID-19, upping the ante on Beijing over its handling of the COVID-19 pandemic.

Trump, who has expressed disappointment over China's handling of the disease, alleged non-transparency and initial non-cooperation with the US on dealing with the crisis. "If they were knowingly responsible, yeah, then there should be consequences. You're talking about, you know, potentially lives like nobody's seen since 1917," he said on Saturday.