US President Donald Trump has appeared to undercut his own intelligence agencies by suggesting he has seen evidence coronavirus originated in a Chinese laboratory.
Earlier the US national intelligence director’s office said it was still investigating how the virus began.
But the office said it had determined Covid-19 “was not manmade or genetically modified”.
China has rejected the lab theory and criticised the US response to Covid-19.
Since emerging in China last year, the virus has killed 230,000 people worldwide including 63,000 in the US.
Simple ways you can help during the pandemic
Has US tested more than rest of world combined?
The pandemic has seen at least 3.2 million people infected, a million of them Americans, since the virus spread from the city of Wuhan.
At the White House on, Mr Trump was asked by a reporter: “Have you seen anything at this point that gives you a high degree of confidence that the Wuhan Institute of Virology was the origin of this virus?”
“Yes, I have. Yes, I have,” said the president, without specifying. “And I think the World Health Organization [WHO] should be ashamed of themselves because they’re like the public relations agency for China.”
Asked later to clarify his comment, he said: “I can’t tell you that. I’m not allowed to tell you that.”
