For decades Israel has neither confirmed or denied it has nuclear weapons. But that policy of ambiguity now appears to have been undermined.

South African government documents, once classified as top secret, are said to show an agreement for Israel to supply nuclear warheads in 1975, during the years of aparthied rule.

Shimon Peres, Israel's incumbent president, is alleged to have been involved in the deal 35 years ago. He has now issued a strongly worded denial.

Yossi Melman, an intelligence correspondent with Israel's Haaretz daily, spoke to Al Jazeera from Tel Aviv about the claims.