Documents unearthed by an American academic indicate that Israel offered to sell nuclear weapons to South Africa in the 1970s. The documents provide the first proof Israel not only has enough nuclear weapons for its own defence but has enough to sell elsewhere.Academic, Sacha Polokow-Suransky, has unearthed documents which appear to indicate Israel offered to sell South Africa nuclear weapons during the era of apartheid. The deal between Israel and South Africa did not proceed. But questions remain as to whether Israel helped South Africa develop nuclear weapons later on. In the 1980s, Mordechai Vanunu, a former technician who worked at Israel's main nuclear facility, revealed the extent of the country's arsenal. Four years ago, former prime minister Ehud Olmert accidentally acknowledged the country's nuclear capability on German television. The claims come as 190 nations are meeting in New York at the Nuclear Non-proliferation Review Treaty. Experts say they are likely to add more pressure on Israel to declare itself a nuclear power.