Did the UK announce the end of aid to South Africa without having the courtesy to inform the South African government first? The British government and Pretoria are offering very different accounts this morning. The South African international relations department said that "proper consultations" had not taken place and denounced the "unilateral" decision. Its statement read:

This is such a major decision with far reaching implications on the projects that are currently running and it is tantamount to redefining our relationship. Ordinarily, the UK government should have informed the government of South Africa through official diplomatic channels of their intentions and allowed for proper consultations to take place, and the modalities of the announcement agreed on.

But on the Today programme this morning, William Hague insisted that the move "shouldn’t have been a surprise" since discussions had been going on "for some months". He added: "No doubt there is some confusion or bureaucratic confusion about that, perhaps, on the South African side. But I’m not going to fling accusations about that. "

International Development Secretary Justine Greening announced the decision to end direct aid, currently worth £19m a year, at a conference of African ministers and business leaders in London yesterday. "I have agreed with my South African counterparts that South Africa is now in a position to fund its own development," she said.

"It is right that our relationship changes to one of mutual co-operation and trade, one that is focused on delivering benefits for the people of Britain and South Africa as well as for Africa as a whole."

In the context of an international development budget of £11bn, the decision to end £19m of aid to a country worth $408.2bn (GDP) might not seem particularly notable, but Labour has seized on the accusation of bad faith. The shadow international development secretary Ivan Lewis declared this morning that it would "reinforce some of the feelings about the apartheid years", later tweeting: "Tories opposed sanctions against apartheid S africa and now end aid to democratic S africa in shabby way. Leaves bitter taste". In a statement issued last night he said:

Justine Greening has serious questions to answer – her claim that her decision was made with the agreement of her South African counterparts has been completely contradicted by the South African Government. This looks like a serious breach of trust with one of our most important strategic partners. Justine Greening must explain why she is saying one thing about her conduct while the South African Government is saying another. Behaving in what looks like a high-handed and patronising fashion towards South Africa is no way to treat one of the world’s key emerging nations and is not in Britain’s national interest.

But beyond the question of whether the South African government was properly consulted, there is a bigger argument here about whether the UK should continue to provide aid to so-called "middle income countries". Having previously ended aid to India, Greening has made her position clear, but as Lewis pointed out on Today this morning, 75 per cent of the world's poorest people now live in middle-income countries, not poor countries. "If we are going to withdraw from every middle-income country in terms of our aid programme, we are not going to be getting to many of the poorest people," he noted.

This argument has the benefit of moral consistency but it's not an easy one to make when the public are already so sceptical of aid spending. A recent ComRes poll showed that just 8 per cent believe the aid budget should be increased, while 77 per cent believe it should be cut.

The figure of £19m may not appear economically significant but the Tories will use this as another example of why Labour would still be big spenders, not wise spenders.