US President Donald Trump has been heavily criticised for halting funding for the World Health Organization (WHO) amid the global coronavirus pandemic.
Philanthropist Bill Gates, a major funder of the WHO, said it was "as dangerous as it sounds".
President Trump said on Tuesday that the body had "failed in its basic duty" in its response to coronavirus.
The head of the WHO said it was reviewing the cuts' impact "to ensure our work continues uninterrupted".
"We regret the decision of the President of the United States to order a halt in the funding to the WHO," Director-General Tedros Adhanom Ghebreyesus said at a press conference, adding that the US has been "a long-standing and generous friend... and we hope it will continue to be so".
Earlier on Twitter he said it was the agency's "singular focus" was to stop the outbreak.
UN Secretary General António Guterres said it was "not the time" to cut funds to the WHO, which "is absolutely critical to the world's efforts to win the war against Covid-19".
Follow live coronavirus updates
Is President Trump right to criticise the WHO?
The WHO row, explained
Mr Trump has accused the WHO of making deadly mistakes and overly trusting China.
"I am directing my administration to halt funding while a review is conducted to assess the World Health Organization's role in severely mismanaging and covering up the spread of the coronavirus," Mr Trump told reporters on Tuesday.
A White House statement on Wednesday said the agency had "failed" the US people.
"The American people deserve better from the WHO, and no more funding will be provided until its mismanagement, cover-ups and failures can be investigated," it read.

Victory662:
I stand with Trump on this. WHO failed us all...

billy69:
I have read that news but I don't think so that it is the right decision, in fact, it will be very dangerous for the world if at this stage they cut down the fund when they need it most. At the same time, people shouldn't be left their houses and also keep proper house cleaning to avoid any unpleasant experience.