The US decision to withdraw all of its HIV and Aids funding from South Africa is likely to cost lives, the head of the UN's HIV agency has warned.

"Please do not take money away because you are taking lives away," UNAids chief Winnie Byanyima told reporters ahead of a UN meeting on the virus, asking Washington to consider a "planned transition".

South Africa does not rely on US-funding for HIV drugs, but the US made a significant contribution to the country's programmes to prevent the spread of the virus.

US officials told the BBC that the funding cut was in part a response to South Africa's alleged failure to protect the white-minority Afrikaner community. An accusation Pretoria rejects.

South Africa's health ministry responded by saying that though it had not been informed of this decision, it had "long been working on a self-reliance plan".

Until 2025, the US was supporting South Africa's efforts to deal with the virus with an estimated $400m (£300m) a year through the President's Emergency Fund for Aids Relief (Pepfar).

During her press briefing on Monday, the UNAids chief said the cuts risk reversing all the progress they have made in their HIV response so far.

There are more than eight million people currently living with HIV in South Africa - higher than anywhere else in the world.

"I call the member states to protect the rights of people living with HIV," Byanyima said, explaining that cuts in financing of international assistance are not from one country.

She said she's "sad" about the Trump administration's decision to withdraw funding, explaining: "America has always been the biggest contributor... we want them to continue." 

According to Byanyima, Pepfar had been providing around 17% of South Africa's HIV response funding.

"Taking it away is taking live-saving support from the most vulnerable people, so that is sad and I would like the United States to reconsider their position."

Since the inauguration of President Donald Trump, relations between the US and South Africa have increasingly soured.

Shortly after he came into office, Trump issued an executive order, alleging that "countless" South African policies dismantled equal opportunities and fuelled violence "against racially disfavored landowners".

This is disputed by the South African government, which says its Black Economic Empowerment policy is needed to correct economic inequality dating from the apartheid era.

Trump has also alleged that there is a "white genocide" taking place in South Africa. The claim has been widely discredited.

Last week, the US State Department confirmed a "phased drawdown" of Pepfar fundingwould now be starting because of "South Africa's failure to make demonstrable progress on policy requests by the administration".