LONDON - Israel offered to sell nuclear warheads to South Africa during the apartheid regime, according to a report in the Guardian newspaper.

Secret South African documents provide the first official documentary evidence of Israel's possession of nuclear weapons, the newspaper says.

It said that "top secret" minutes of meetings between senior officials from the two countries in 1975 showed that South Africa's Defence Minister, P.W. 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 newspaper said the two men also signed a wide-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 newspaper made the revelations after American academic Sasha Polakow-Suransky uncovered the documents as part of research for a book on the close relationship between the two countries.

It said the documents also provided evidence Israel had nuclear weapons despite its policy of "ambiguity" in neither confirming nor denying their existence.

Israel tried to stop South Africa's post-apartheid Government declassifying the documents which show the apartheid-era military wanted the missiles as a deterrent and for potential strikes against neighbouring states.

Polakow-Suransky's book The Unspoken Alliance: Israel's secret alliance with apartheid South Africa, is to be published in the United States this week.