US President Donald Trump's administration said on Friday the United States was rejecting changes agreed last year for the World Health Organization on its pandemic response, saying they violated US sovereignty.

Trump, on returning to office on January 20, immediately began the withdrawal of the United States from the UN body, but the State Department said the language from last year would still have been binding on the United States.

US Secretary of State Marco Rubio and Health and Human Services Secretary Robert F Kennedy, who is a longtime critic of vaccines, said that the changes "risk unwarranted interference with our national sovereign right to make health policy."

"We will put Americans first in all our actions, and we will not tolerate international policies that infringe on Americans' speech, privacy or personal liberties," they said in a joint statement.

Rubio and Kennedy disassociated the United States from a series of amendments to the International Health Regulations, which provide a legal framework for combating diseases, agreed last year at the World Health Assembly in Geneva.

The amendments included a stated "commitment to solidarity and equity" in which a new group would study the needs of developing countries in future emergencies.

Countries have until Saturday to lodge reservations about the amendments. Conservative activists and vaccine sceptics in Britain and Australia, which both have left-leaning governments, have waged public campaigns against the changes.

The amendments came about when the Assembly failed at a more ambitious goal of sealing a new global agreement on pandemics.

Most of the world finally sealed a treaty this May, but the United States did not participate as it was in the process of withdrawing from the World Health Organization.

The United States, then under President Joe Biden, took part in the May-June 2024 negotiations, but said it could not support consensus as it demanded protections for US intellectual property rights on vaccine development.

Rubio's predecessor, Antony Blinken, had welcomed the amendments as progress. (AFP)