President Donald Trump announced on Friday he would withdraw funding from the World Health Organization, end Hong Kong's special trade status and suspend visas of Chinese graduate students suspected of conducting research on behalf of their government — escalating tensions with China that have surged during the coronavirus pandemic.

Trump has been expressing anger at the WHO for weeks over what he has portrayed as an inadequate response to the initial outbreak of the coronavirus in China's Wuhan province late last year.

The president said in a brief White House announcement that Chinese officials 'ignored' their reporting obligations to the WHO and pressured the organisation to mislead the public about an outbreak that has now killed more than 100,000 people in the US.

'We have detailed the reforms that it must make and engaged with them directly, but they have refused to act,' the president said. 'Because they have failed to make the requested and greatly needed reforms, we will be today terminating the relationship.'

The US is the largest source of financial support for the WHO and its exit is expected to significantly weaken the organisation. Trump said the US would be 'redirecting' the money to 'other worldwide and deserving urgent global public health needs', without providing specifics.

He noted that the US contributes about $450 million to the world body while China provides about $40 million.

Critics of the administration's decision to cut funding called it misguided, saying it would undermine an important institution that is leading vaccine development efforts and drug trials to address the Covid-19 outbreak.

'Severing ties with the World Health Organization serves no logical purpose and makes finding a way out of this public health crisis dramatically more challenging,' said Dr Patrice Harris, president of the American Medical Association.

Senator Chris Murphy called it a distraction that would 'hand over' the organisation to China. 'Leaving castrates our ability to stop future pandemics and elevates China as the world's go-to power on global health,' said the Connecticut Democrat.

The WHO had no immediate comment.

Simmering tensions over Hong Kong

Tensions over Hong Kong have been increasing for more than a year as China has cracked down on protesters and sought to exert more control over the former British territory.

Trump said the administration would begin eliminating the 'full range' of agreements that had given Hong Kong a relationship with the US that mainland China lacked, including exemptions from controls on certain exports. He said the state department would begin warning US citizens of the threat of surveillance and arrest when visiting the city.

'China has replaced its promised formula of one country, two systems, with one country, one system,' he said.

Secretary of State Mike Pompeo notified Congress on Wednesday that Hong Kong is no longer deserving of the preferential trade and commercial status it has enjoyed from the US since it reverted to Chinese rule in 1997.

It's not yet clear what impact the decision will have on US companies that operate in Hong Kong or on the city's position as Asia's major financial hub, or how China will react to the decision.

'The downward spiral in the bilateral relationship has now reached lows not seen since the June 4, 1989, Tiananmen massacre, and there is little reason to expect things to get better soon,' said Dexter Tiff Roberts, an Asia expert at the Atlantic Council, which publishes non-partisan policy analysis.

Bar on Chinese graduate students

The president said the US would be suspending the entry of Chinese graduate students who are suspected of taking part in an extensive government campaign to acquire trade knowledge and academic research for the country's military and industrial development.

Allowing their continued entry to the country would be 'detrimental to the interests of the US', Trump said in an order released after the White House announcement.

Revocation of the visas has faced opposition from US universities and scientific organisations that depend on tuition fees paid by Chinese students to offset other costs and fear possible reciprocal action from Beijing that could limit their access to China.

The order issued by the president included an exemptions for students whose work was not expected to benefit the Chinese military.

China seemed to signal in recent days that it was hoping to ease tensions. Premier Li Keqiang told reporters on Thursday that both countries stood to gain from cooperation, and to lose from confrontation, because their economies have become so interconnected.

'We must use our wisdom to expand common interests and manage differences and disagreements,' Li said.

Still, the country has insisted that its control of Hong Kong is an internal matter and it has disputed that it mishandled the response to the virus.