Beijing on Tuesday accused Donald Trump of smearing China and shirking American responsibilities to the World Health Organization, after the US president threatened to pull out of the UN health body.

The American leader has been locked in a bitter war of words with Beijing, alleging it covered up the initial outbreak in central China late last year before the disease spread globally, causing economic devastation and claiming lives across the planet.

Trump on Monday called the WHO a "puppet of China" before tweeting a letter he had sent to the organisation's chief Tedros Adhanom Ghebreyesus threatening to make permanent a temporary freeze on funding from the US.

China in response accused Trump of trying to "smear China" and "shirk responsibility and bargain over its international obligations to the WHO", foreign ministry spokesman Zhao Lijian said at a regular press briefing Tuesday.

"The US leader’s open letter you mentioned is full of hints, 'perhaps', and 'maybes', and tries to use specious methods to mislead the public, and achieve the goals of smearing China’s anti-virus efforts, and shirk responsibility for the United States' own insufficient response," Zhao said. "The US tries to use China as an issue to shirk responsibility and bargain over its international obligations to the WHO. This is a miscalculation and the US has picked the wrong target."

More than 317,000 people have died of COVID-19 out of nearly 4.8 million infections worldwide, and governments are scrambling to contain the virus while seeking ways to resuscitate their hammered economies. Zhao added the US was attempting to deflect from its own "insufficient prevention and control" against the virus.

With more fatalities and cases in the United States than any other country by far, under-pressure Trump has blamed the WHO for not doing enough to combat its initial spread. "The only way forward for the World Health Organization is if it can actually demonstrate independence from China," Trump's letter read.

China urges the US to "stop shifting the blame" and instead focus on containing the virus, Zhao said at a regular press conference.

Earlier Monday the WHO said it would launch an independent review of the response to the coronavirus pandemic, and Chinese President Xi Jinping said China supports a "comprehensive evaluation" of the global response to the pandemic after it has been brought under control. Governments including the US and Australia had previously called for an investigation into the origins of the virus.

But Zhao said Tuesday that the draft motion currently under discussion at the World Health Assembly is "completely different from the so-called 'independent international inquiry' into the pandemic previously mentioned by Australia".

He added that Australia should be willing to "change its ways" and "completely abandon its political manipulation of the pandemic". Beijing has furiously denied US allegations that it played down the threat, and Xi reiterated at the WHO's World Health Assembly on Monday that his nation had been "open, transparent and responsible" during the crisis.