Israel on Monday vehemently rejected claims in a British newspaper that it offered to sell nuclear warheads to Apartheid-era South Africa in 1975.

"There exists no basis in reality for the claims published this morning by The Guardian that in 1975 Israel negotiated with South Africa the exchange of nuclear weapons," the president's office said in a statement.

"Unfortunately, The Guardian elected to write its piece based on the selective interpretation of South African documents and not on concrete facts," said the statement. "Israel has never negotiated the exchange of nuclear weapons with South Africa. "There exists no Israeli document or Israeli signature on a document that such negotiations took place."

The Guardian newspaper said Sunday that documents uncovered by a U.S. academic during research for a book on Israel's ties with South Africa provided the first hard proof that Israel has nuclear weapons. Israel maintains an official policy of "nuclear ambiguity" over whether it is an atomic power.

The Guardian said documents declassified by South Africa's post-apartheid government at the request of author Sasha Polakow-Suransky included top-secret minutes of meetings between senior officials of the two countries in 1975.

Those papers, the newspaper said, showed that South Africa's defense minister at the time, P.W. Botha, asked warheads and his counterpart Shimon Peres, now Israel's president, offered them in "three sizes". The Guardian claimed that this referred to conventional, chemical and atomic weapons.

Asked about the report, Peres spokeswoman Ayelet Frisch said: "There is no truth to the Guardian report."

"We regret that the newspaper did not seek a comment from the president's office. If it had done so, it would have discovered that the story is wrong and baseless," she added.

According to the Guardian report, the alleged nuclear deal did not go ahead, partly because of the cost.

Speculation about Israeli-South African nuclear cooperation was raised in 1990 when a U.S. satellite detected a mysterious flash over the Indian Ocean. The U.S. television network CBS reported it was a nuclear test carried out by the two countries.