The United States on Thursday accused the World Health Organization of putting politics first by ignoring Taiwanese warnings over China's coronavirus outbreak, laying out its case against the UN body.

President Donald Trump has threatened to withhold US funding for the WHO, which is at the forefront of fighting the pandemic that has infected more than 1.5 million people worldwide.

Elaborating on Trump's case, the State Department said the WHO was too late in sounding the alarm over COVID-19, showed too much deference to China and questioned why it did not pursue a lead from Taiwan.

The United States is "deeply disturbed that Taiwan's information was withheld from the global health community, as reflected in the WHO's January 14, 2020 statement that there was no indication of human-to-human transmission," a State Department spokesperson said.

"The WHO once again chose politics over public health," she said, criticizing the WHO for denying Taiwan even observer status since 2016.

The WHO's actions have "cost time and lives," the spokesperson said.

Taiwan, which has succeeded in preventing a major outbreak despite its proximity and ties to China, warned the WHO on December 31 of human-to-human transmission, Vice President Chen Chien-Jen has said.