A global health organisation has warned that one million children could die from preventable diseases if the US terminates its financial support.

Dr Sania Nishtar - head of Gavi, an alliance that buys critical vaccines for developing countries - told the BBC a cut in US funding would have a "disastrous impact on global health security".

This follows a report in the New York Times that the Trump administration intends to terminate Gavi's funding - the US is the alliance's third largest donor.

Gavi has not received a termination notice from the US but it was "engaging with the White House and Congress" to secure $300m (£230m) for its activities in 2025, and longer-term funding, Dr Nishtar said.

The US has pledged $1.6bn for the 2026-2030 period - about 15% of Gavi's total funding.

Since taking office in January 2025, US President Donald Trump has made it clear he wants overseas spending to be closely aligned with his "America First" approach.

The international development sector has been braced for a profound effect on humanitarian programmes around the world.

The US Agency for International Development (USAID) was one of the first agencies targeted by Elon Musk's Department of Government Efficiency (Doge) for cuts at the start of 2025, when the Trump administration ordered a 90-day freeze of all US foreign aid.

Of the 500 million children that need to be immunised around the world, 75 million would miss out if Gavi lost US funding, said Dr Nishtar, resulting in deaths from preventable diseases like measles, tuberculosis, pneumonia and polio.

This would also mean that governments and health agencies' ability to keep the world safe through vaccine stockpiles against diseases such as Ebola, cholera and mpox would be compromised, she said.

Medical charity Médecins Sans Frontières (MSF) agrees with Gavi's warning about the potential funding cuts.

"The consequences of this political decision will be catastrophic," said MSF USA chief programs officer Carrie Teicher.

The Africa Centres for Disease Control and Prevention (Africa CDC) "fully supports" Gavi and is "engaging" with US authorities on the disruption caused by the withdrawal of US funding for major programmes, said Africa CDC emergencies incident manager Dr Ngongo Ngashi.

He added: "We are prioritising routine vaccines but we also know how crucial vaccines for emergencies are."

Dr Ngashi also said it was "critical that we find our own funding streams - that are not dependent on the decision of partners" and which help Africans contribute "to advancing public health".

Gavi has said it will try to further broaden its donor base. Indonesia, a country that has previously been a recipient of Gavi's assistance, became a donor last year.

"As a lean and efficient organisation where 97 cents in every dollar raised goes towards our immunisation programmes, it is impossible to consider that any cut in funding by the US would not have disastrous implications for global health and for the safety of people everywhere," Dr Sania Nishtar said.

The BBC has contacted the US State Department, which runs what remains of USAID, for comment.