The South African government on Thursday said it would summon the Zambian high commissioner to explain his vice-president's insistence that he hated "backward" South Africans.
In an interview with Britain's Guardian newspaper, vice president Guy Scott discarded normal diplomatic niceties and vented his feelings about inhabitants of the continent's leading economy.
"The South Africans are very backward in terms of historical development."
He did not stop there.
"I hate South Africans. That's not a fair thing to say because I like a lot of South Africans but they really think they're the bees' knees and actually they've been the cause of so much trouble in this part of the world.
"I dislike South Africa for the same reason that Latin Americans dislike the United States, I think. It's just too big and too unsubtle."
He also compared South African President Jacob Zuma to the last apartheid president FW de Klerk.
That was too much for South Africa's government, which is now demanding an explanation.
"South Africa has taken note of the negative remarks on South Africa attributed to Mr Guy Scott."
"We shall be summoning the High Commissioner of Zambia to South Africa to the Department of International Relations and Cooperation to seek an explanation behind the remarks and what it means in the context of our bilateral relations."