Donald Trump said his planned Friday trip to US Centers for Disease Control and Prevention was axed due to a suspected coronavirus case at the Atlanta facility that turned out to be false – so he may show up there after all.

"So I may be going," he told reporters while signing a $8.3bn emergency virus aid bill. "We're going to see if they can turn it around."

The president said the person who turned out to not have the virus was "at a high level" of the CDC, but did not name anyone specifically.

As the president signed an $8.3bn counter-virus spending bill into law, Health and Human Services Secretary Alex Azar told reporters he will go to Atlanta on Friday instead. But Mr Trump left open the door that he also would go.

"They thought there was a problem at CDC," he said, but the possible case "turned out negative."

"So we'll see if we can do it," he said of going to the Atlanta facility. "They now found out that was a negative test."

He has been criticised for downplaying the threat to Americans, and for being sometimes-flippant and dismissive about the virus, which he said Friday "will eventually go away."

Asked if US and global markets, which have lost substantial value as the virus has spread, Mr Trump said he expects them to quickly bounce back.

"I think we're in great shape," he said. "This came aboutn unexpectedly months ago."