Secretary of State Mike Pompeo on Monday condemned the exclusion of Taiwan from the World Health Organization's annual meeting, saying it proved US charges that the UN body was beholden to China.
The WHO member states at the annual meeting delayed discussion on whether to grant observer status to Taiwan, which Beijing considers a province awaiting reunification and seeks to exclude from all international organizations.
Pompeo said WHO Director-General Tedros Adhanom Ghebreyesus, who has been harshly criticized by President Donald Trump's administration, "had every legal power and precedent" to include Taiwan in the meeting.
"Yet he instead chose not to invite Taiwan under pressure from the People's Republic of China," Pompeo said in a statement.
"The Director-General's lack of independence deprives the Assembly of Taiwan's renowned scientific expertise on pandemic disease, and further damages the WHO's credibility and effectiveness at a time when the world needs it the most."
Taiwan has enjoyed remarkable success in combatting the pandemic, with only seven deaths and some 400 infections despite its proximity and close commercial links with mainland China, where the disease was first identified.
"The PRC's spiteful action to silence Taiwan exposes the emptiness of its claims to want transparency and international cooperation to fight the pandemic, and makes the difference between China and Taiwan ever more stark," Pompeo said.
"Taiwan is a model world citizen, while the PRC continues to withhold vital information about the virus and its origins," he said.
Trump has accused the WHO of not sounding an alarm early enough and of blindly taking China's word after the virus was identified late last year in Wuhan.
Critics say that Trump, who himself had earlier praised China's response, is trying to divert attention from his own handling of the pandemic in the United States, which has suffered by far the highest death toll.