US Secretary of State Mike Pompeo has claimed the virus originated in a Chinese lab - a claim rubbished by Beijing.

Australian Prime Minister Scott Morrison says his country is working closely with the US, but isn't endorsing the lab theory.

"We can't rule out any of these arrangements... but the most likely has been in a wildlife wet market."

He added: "What really is important is that we have a proper review that looks into the sources of these things."