Muhammad al-Baradai, the head of the International Atomic Energy Agency, said Israel and its neighbours should eliminate all weapons of mass destruction from the region.
The UN General Assembly and IAEA General Conference have adopted 13 resolutions since 1987 appealing to Israel to join the treaty, but all have been ignored.
Israel's nuclear programme was exposed in 1986 by Israeli nuclear scientist Mordechai Vanunu.
After a British newspaper published the revelations, Mossad agents kidnapped Vanunu in Italy and illegally smuggled him back to Israel.
He has now spent 17 years in jail, 11 of which were in a tiny solitary confinement cell - and he has just had his appeal for parole denied.
Vanunu will stay in jail until 2004, when his term is expected to end.
Neil Kingsnorth, a spokesman for the London-based Campaign for Nuclear Disarmament, told Aljazeera.net in December that Israel is estimated to have up to 200 nuclear warheads.
Vanunu blew the whistle on
Israel's nuclear programme
If deployed, they would be sufficient to obliterate the whole region.
Kingsnorth added that the whole nuclear debate is replete with hypocrisy.
"The US and Great Britain have thousands of nuclear warheads between them but are refusing to give them up. They are trying to make this false distinction between good states that can have nuclear weapons and bad ones who can't," he said.
"In practice, the good ones are the ones that are willing to work with them and the bad ones are the ones who are not. I think that is an incredible oversimplification of a complex international situation."
He added: "Israel should own up to having nuclear weapons and sign the Non-Proliferation Treaty. If countries like Israel set an example, non-nuclear states would lose the incentive to acquire these weapons. Then we could make strides to nuclear free world."