Eight people in South Sudan, including five children, died on a three-hour walk to seek medical treatment for cholera after US aid cuts forced local health services to close, the UK-based charity Save the Children said on Wednesday.

The deaths last month are among the first to be directly attributed to cuts imposed by US President Donald Trump after entering office on January 20, which he said were to ensure grants were aligned with his "America First" agenda.

"There should be global moral outrage that the decisions made by powerful people in other countries have led to child deaths in just a matter of weeks," said Christopher Nyamandi, Save the Children's country director in South Sudan.

Experts have warned that the cuts - including the cancellation of more than 90% of USAID's contracts - could cost millions of lives in the coming years due to malnutrition, AIDS, tuberculosis, malaria and other diseases.

The US State Department said it did not have information about the deaths reported by Save the Children. A spokesperson said many US government programmes providing lifesaving aid in South Sudan remained active but that support for medical services had also been used to enrich the country's leaders.

"While emergency lifesaving programmes continue, we will not, in good conscience, ask the American taxpayer to provide assistance that effectively subsidises the irresponsible and corrupt behaviour of South Sudan’s political leaders," the spokesperson said.

South Sudan's government has in the past acknowledged a significant amount of public corruption but denied specific accusations of graft, including against President Salva Kiir's family.

Humanitarian aid to the country is often channelled through non-governmental organisations, largely because of corruption concerns.

Save the Children supported 27 health facilities in eastern South Sudan's Jonglei State until earlier this year when the US cuts forced seven to shut completely and 20 to close partially, the organisation said in a statement.

US funded transport services to take people to hospital in the main local town also stopped for lack of funds, which meant the eight cholera patients had to walk in nearly 40°C heat to seek treatment at the nearest health facility, it said.

Three of the children were under the age of 5, Nyamandi said.

Besides the US cuts, more gradual reductions by other donors have strained the humanitarian response in South Sudan. Save the Children expects to spend $30-million in the country in 2025, down from $50-million last year, Nyamandi said.

Over a third of South Sudan's roughly 12-million people have been displaced by either conflict or natural disaster, and the United Nations says the country could be on the brink of a new civil war after fighting broke out in February in the northeast.

A cholera outbreak was declared last October. More than 22 000 cases had been recorded as of last month, causing hundreds of deaths, the World Health Organization has said.