US President Donald Trump leaves a news conference on the novel coronavirus, COVID-19, in the Rose Garden of the White House in Washington, DC on May 11, 2020. Photo: AFP

US President Donald Trump has formally notified Congress that the US has officially moved to withdraw from the World Health Organization (WHO), Democratic Senator Bob Menendez said on Tuesday.

"Congress received notification that POTUS officially withdrew the US from the @WHO in the midst of a pandemic," tweeted by Menendez, ranking member of the Senate Committee on Foreign Relations.

"To call Trump's response to COVID chaotic & incoherent doesn't do it justice. This won't protect American lives or interests - it leaves Americans sick & America alone," he added.

Stéphane Dujarric, spokesman for the UN secretary-general, confirmed the US had notified it of its withdrawal, effective as of 6 July 2021, BBC reported.

Trump and his administration repeatedly assailed the WHO for months and threatened to cut ties with the organization. Experts and Democrats criticized that the Trump administration was trying to shift blames of its mishandling of COVID-19 response and would be counterproductive to addressing the public health crisis.

Trump said in late May that his country is "terminating" its relationship with the WHO. In a letter to WHO Director-General Tedros Adhanom Ghebreyesus earlier that month, Trump threatened to permanently cut off the nation's funding to the WHO and "reconsider our membership" if the international body does not commit to what he called "substantive improvements within the next 30 days."

Trump announced in mid-April that his administration would halt US funding to the WHO.

The US has reported more than 2.96 million COVID-19 cases with over 130,000 deaths, according to Johns Hopkins University. Both figures are far higher than those in any other country or region.