The "top secret" minutes of meetings between senior officials from the two countries in 1975 show that South Africa's defence minister, PW Botha, asked for the warheads and Shimon Peres, then Israel's defence minister and now its president, responded by offering them "in three sizes". The two men also signed a broad-ranging agreement governing military ties between the two countries that included a clause declaring that "the very existence of this agreement" was to remain secret.
The documents, uncovered by an American academic, Sasha Polakow-Suransky, in research for a book on the close relationship between the two countries, provide evidence that Israel has nuclear weapons despite its policy of "ambiguity" in neither confirming nor denying their existence.
The Israeli authorities tried to stop South Africa's post-apartheid government declassifying the documents at Polakow-Suransky's request and the revelations will be an embarrassment, particularly as this week's nuclear non-proliferation talks in New York focus on the Middle East.
They will also undermine Israel's attempts to suggest that, if it has nuclear weapons, it is a "responsible" power that would not misuse them, whereas countries such as Iran cannot be trusted.
The memos and minutes that confirm Israel's nuclear stockpiles
Israel's nuclear weapons: The end of nods
Mordechai Vanunu: trapped and kidnapped by the Mossad and jailed by Israeli authorities for speaking about Israel's nuclear capability
Israel's nuclear ambiguity
Israel's apartheid roads
This also means that Israel intends to use its nuclear weapons to maintain its apartheid and violations of Palestinian rights.
The Russell tribunal on Palestine (Bertrand Russell versus lord Balfour)