The head of the World Health Organization (WHO) on Saturday pushed back against Washington's stated reasons for withdrawing from the UN health agency, dismissing U.S.criticism of the WHO as "untrue."

Tedros Adhanom Ghebreyesus warned that the U.S. announcement this week of having formally withdrawn from the WHO "makes both the U.S. and the world less safe."

He added on an X post, "Unfortunately, the reasons cited for the U.S. decision to withdraw from the WHO are untrue," and insisted that the WHO "has always engaged with the U.S., and all Member States, with full respect for their sovereignty."

U.S. Secretary of State Marco Rubio and U.S. Health Secretary Robert F. Kennedy Jr. announced in a joint statement Thursday that Washington had formally withdrawn from the WHO.

They accused the agency of numerous "failures during the Covid-19 pandemic" and of acting "repeatedly against the interests of the United States."

The WHO has not yet confirmed that the U.S. withdrawal has taken effect.

Withdrawal 'raises issues'

The row came as Washington struggled to dislodge itself from the WHO, a year after U.S.President Donald Trump signed an executive order to that effect.

The one-year withdrawal process reached completion on Thursday, but Kennedy and Rubio expressed regret in their statement that the UN health agency had "not approved our withdrawal and, in fact, claims that we owe it compensation."

The WHO has highlighted that when Washington joined the organization in 1948, it reserved the right to withdraw as long as it gave one year's notice and had met "its financial obligations to the organization in full for the current fiscal year."

The U.S., which announced its withdrawal from the WHO a year ago, has yet to pay its outstanding membership dues, a WHO press official has confirmed.

"As of today, the USA has not paid the invoiced amounts for its assessed contributions for the biennium 2024-2025," a WHO press official said in an email to Xinhua on Wednesday.

According to a recent report by the National Public Radio (NPR), a U.S.-based media organization, the overdue sum totals approximately $278 million.

"The notification of withdrawal raises issues," the WHO said Saturday, adding that the topic would be examined during the WHO's Executive Board meeting next month and by the annual World Health Assembly meeting in May.

"We hope the U.S. will return to active participation in the WHO in the future," Tedros said Saturday.

"Meanwhile, the WHO remains steadfastly committed to working with all countries in pursuit of its core mission and constitutional mandate: the highest attainable standard of health as a fundamental right for all people."

(With input from agencies)