US President Donald Trump again lashed out at China Wednesday over the coronavirus pandemic, blaming Beijing for "mass Worldwide killing."

The early morning tweet, which also referred to an unidentified "wacko in China," was the latest heated rhetoric from the White House, where Trump is making attacks on Beijing a centerpiece of his November reelection bid.

"It was the 'incompetence of China', and nothing else, that did this mass Worldwide killing," the president tweeted.

The virus first appeared in the Chinese city of Wuhan last December and spread rapidly around the world, killing more than 323,000 people at the latest count, and triggering huge economic damage.

Trump initially played down the seriousness of the threat and said repeatedly that China was addressing the outbreak. He later pivoted to blaming China for allowing the international spread.

The White House has also suggested, without offering evidence so far, that the virus originated in a laboratory and was accidentally released. Trump has made repeated but vague threats of retaliation against the chief US economic rival. He has also threatened to break off US funding to the World Health Organization or WHO over what he says was its assistance to China in covering up the extent of the outbreak.