The Trump administration has formally notified the United Nations of its decision to withdraw the US from the World Health Organization, officials said, breaking off ties with the global health body amid the expanding coronavirus pandemic.

The US has accused the WHO of siding with China on the outbreak of the virus, which originated in the Chinese city of Wuhan late last year, alleging the health body misled the world resulting in deaths of over half a million people globally, including over 130,000 in America.

In April, the US stopped funding to WHO as the Trump administration reviewed the ties. A month later, President Donald Trump announced the US was terminating the relationship. The US is the largest funder to the world health, contributing more than USD450 million per annum, while China's contribution to the health body is about one-tenth of that of the US.

"I can say that on 6 July 2020, the United States of America notified the secretary-general, in his capacity as depositary of the 1946 Constitution of the World Health Organization, of its withdrawal from the World Health Organization, effective on 6 July 2021, said St phane Dujarric, spokesman for the UN secretary-general, in a statement.

Dujarric said the secretary-general is in the process of verifying with the WHO whether all the conditions for such withdrawal are met.

The United States has been a party to the WHO Constitution since June 21, 1948. Its participation was accepted by the World Health Assembly with certain conditions set out by the US for its eventual withdrawal from this world body.

The said conditions include giving a one-year notice, meaning the withdrawal won't go into effect until July 6 next year, raising the possibility the Trump administration's decision could be reversed by a new government after the presidential elections in November this year.

The decision was criticised by several Congressmen, who said it "would be a bad policy".

To call Trump's response to COVID chaotic and incoherent doesn't do it justice. This won't protect American lives or interests it leaves Americans sick and America alone, tweeted Senator Robert Menendez, a ranking member of the Senate Foreign Relations Committee.

Congressman Eliot Engel, Chairman of the House Committee on Foreign Affairs, said, It would be bad policy to pull out of the world's leading body coordinating global health efforts under any circumstances, but to do so during a global pandemic is utterly baffling, especially against the backdrop of 130,000 American lives lost.

Remaining in the WHO and exerting American leadership would boost international efforts to develop a vaccine and strengthen other countries' health systems to better address future outbreaks, he said.

Deflecting blame onto the WHO won't reverse the administration's mistakes or undo the suffering our country has endured. The president needs to get serious about stopping this pandemic's lethal spread by restoring our membership in the WHO, ramping up testing, and encouraging everyone to practice social distancing and wear masks, Engel said.

To withdraw the US from the WHO at the height of a global pandemic is self-defeating and dangerous, said House Majority Leader, Steny Hoyer.

Not only will this withdrawal hurt global efforts to develop and deploy critical vaccines, but it will also remove our ability to have a say in the operations and future of that organization, yielding much influence to China, he said.

Indian-American Congressman Ami Bera said America lost its best chance to defeat the virus once the president began to minimize the pandemic and shift blame onto others, instead of assuming responsibility and actually leading the country through this crisis.

Today's decision comes as no surprise, he said.

No response has been perfect, including the WHO's. But the WHO is playing a critical role by coordinating the global response and providing important guidance and information about the virus. It is this information and guidance that has helped countries in Europe and Asia tackle and contain the virus. They bent the curve. Our cases are increasing. If the WHO is to blame: why has the US been left behind while many countries from South Korea to New Zealand to Vietnam to Germany return to normal? Bera said.

Senator Patty Murray, a ranking member of the Senate Health, Education, Labour, and Pensions Committee, also slammed the Trump administration.

This is an abdication of America's role as a global leader and it is the opposite of putting America first it will put America at risk. Refusing to work with our partners across the world to fight this pandemic will only prolong the crisis, further undermine our international standing, and leave us less prepared for future crises. President Trump needs to realize this crisis doesn't recognize borders and hiding from it or passing the blame won't make it go away or make him any less responsible, Murray said.

Senator Jeff Merkley, the top Democrat on the Senate Foreign Relations subcommittee that oversees multilateral institutions, said Trump and Secretary of State Mike Pompeo are delivering a huge win for China and a huge blow to the American people.

By pulling out of the WHO, President Trump is strengthening Chinese leadership and power, both within the WHO and more broadly within the international community. This is a huge mistake that damages American interests, Merkley said.