WASHINGTON: Hundreds of contractors working for the US Agency for International Development are being put on unpaid leave and some are being terminated after US President Donald Trump imposed a sweeping freeze on US foreign aid worldwide.

The furloughs come even as US Secretary of State Marco Rubio issued overnight an additional waiver for "life-saving humanitarian assistance" while Washington undertakes the 90-day review Trump initiated just hours after he came into office on Jan 20.

Despite the waiver, health and humanitarian groups around the world on Wednesday were still uncertain if and how they could resume work and whether their programs were covered by the exception.

The administration says it is conducting the review to ensure the tens of billions of dollars worth of US foreign assistance worldwide is aligned with Trump's "America First" foreign policy and not a waste of taxpayer money.

The United States is by far the largest donor of aid globally. In fiscal year 2023, it disbursed US$72 billion (RM316 billion) of assistance worldwide on everything from women's health in conflict zones to access to clean water, HIV/AIDS treatments, energy security and anti-corruption work.

The State Department said on Wednesday that the pause in assistance stopped the provision of "condoms and other contraceptive services in Gaza", clean energy programs for women in Fiji and family planning throughout Latin America, among other programs, saying that so far over US$1 billion in spending "not aligned with an America First agenda has been prevented."