The World Health Organization (WHO) said Wednesday it regrets the US decision to halt funding to the agency and that it was assessing the possible impact.

US President Donald Trump announced Tuesday that he is halting funding to the WHO while his administration reviews the organization's handling of the novel coronavirus crisis. He accused the WHO of not making correct and timely calls about the threat and called the organization "China centric".

"We regret the decision of the president of the United States to order a halt in funding to the WHO," said WHO Director-General Tedros Adhanom Ghebreyesus during a virtual news conference from Geneva.

He praised the US for being a longstanding and generous friend to the WHO, saying "we hope it will continue to be so".

Tedros said the WHO is reviewing the impact on its work from any withdrawal of US funds and will work with its partners to fill any financial gaps it faces to ensure its work continues uninterrupted.

Dr Robert Redfield, the director of the US Centers for Disease Control and Prevention, on Wednesday praised the WHO in tones at odds with the president's harsh criticism. He told CBS News that questions about the WHO's pandemic response should be left until "after we get through this".

House Speaker Nancy Pelosi denounced Trump's call to halt funding, promising Wednesday to "swiftly challenge" the move, calling it "dangerous" and "illegal".

"As he has since Day 1, the president is ignoring global health experts, disregarding science and undermining the heroes fighting on the front line, at great risk to the lives and livelihoods of Americans and people around the world," Pelosi said in a statement. "This is another case, as I have said, of the president's ineffective response, that 'a weak person, a poor leader, takes no responsibility. A weak person blames others.'"

The US Chamber of Commerce said Trump's action cut against US interests. "Cutting the WHO's funding during the COVID-19 pandemic is not in US interests given the organization's critical role assisting other countries — particularly in the developing world — in their response," the group's executive Vice-President Myron Brilliant said.

"Deeply regret US decision to suspend funding to @WHO," European Union foreign policy chief Josep Borell tweeted. "There is no reason justifying this move at a moment when their efforts are needed more than ever to help contain & mitigate the #coronavirus pandemic."

The Chinese Foreign Ministry expressed its "grave concerns" over Washington's decision to halt its funding for the WHO, saying the move will undermine the ability of the organization and international cooperation in tackling the virus.

Foreign Ministry spokesman Zhao Lijian made the remark at a daily news conference Wednesday after Trump announced that his administration is withholding the US annual contribution of $400 million to the WHO and will conduct a review of the global organization's handling of the COVID-19 pandemic.

As the whole world is threatened by the novel coronavirus, the suspension of funding will affect all countries, including the US itself, as well as countries that are less able to contain the outbreak, Zhao said, urging the US to support the WHO in leading global disease control efforts.

Zhao said the WHO, a specialized agency of the United Nations' Sustainable Development Group, is the most authoritative and professional international organization in ensuring worldwide public health security and has an irreplaceable role to play in coping with global health crises. China will continue to support the organization in tackling the pandemic, Zhao added.

China has donated $20 million to the WHO to support its disease-control efforts and will continue to support it to the best of the country's ability, Zhao said.

Wang Yiwei, a professor at the School of International Studies of Renmin University of China, said the US is "shifting blame" and that its decision reflects Washington's "America First" thinking.

Whether the world will succeed in containing the pandemic depends on how countries with weaker abilities cope with the challenge, and the US will be safe only when all humanity overcomes the disease, he said.