World Health Organization officials on Wednesday denied that the body was "China-centric" and said that the acute phase of a pandemic was not the time to cut funding, after US President Donald Trump said he would put contributions on hold.
The United States is the top donor to the Geneva-based body which Trump said had issued bad advice during the new coronavirus outbreak.
US contributions to WHO in 2019 exceeded $400 million (£324.73 million), almost double the 2nd largest country donor, according to figures from the US State Department. China contributed $44 million, it said.
"We are still in the acute phase of a pandemic so now is not the time to cut back on funding," Dr Hans Kluge, WHO regional director for Europe, told a virtual briefing when asked about Trump's remarks.
Dr Bruce Aylward, senior advisor to the WHO Director-General, also defended the UN agency's relationship with China, saying its work with Beijing authorities was important to understand the outbreak which began in Wuhan in December.
"It was absolutely critical in the early part of this outbreak to have full access to everything possible, to get on the ground and work with the Chinese to understand this," he told reporters.
"This is what we did with every other hard-hit country like Spain and had nothing to do with China specifically."
Aylward, who led a WHO expert mission to China in February, defended WHO recommendations to keep borders open, saying that China had worked "very hard" to identify and detect early cases and their contacts and ensure they did not travel.
"China worked very, hard very early on, once it understood what it was dealing with, to try and identify and detect all potential cases to make sure that they got tested to trace all the close contacts and make sure they were quarantined so they actually knew where the virus was, where the risk was," he said.
"Then they made it very clear that these people would not and could not travel within the country, let alone internationally," he added.
WHO Director-General Tedros Adhanom Ghebreyesus has been lavish in his praise of China from early in the outbreak, praising President Xi Jinping's "rare leadership".
David Heymann, a professor at the London School of Hygiene & Tropical Medicine who led WHO's response to the 2003 SARS outbreak, said that any US funding cut would be a huge blow.
"If the WHO loses its funding it cannot continue to do its work. It works on a shoe-string budget already," Heymann said in London. "Of course it would be disastrous for the WHO to lose funding."