The head of UN's nuclear watchdog, Mohamed ElBaradei, has said he has seen a "glimmer of hope" for a nuclear-free Middle East.
ElBaradei says nuclear weapons have no place in the Middle East
After meeting Ariel Sharon, he said the Israeli prime minister had for the first time talked about the establishment of a nuclear-free zone.
Mr ElBaradei quoted Mr Sharon as saying that this could only be achieved once there was peace in the region.
This was not a change of policy, he said, but it was a new form of words.
"The prime minister this morning affirmed to me that Israel's policy [is] that in the context of peace, establishment of peace in the Middle East, Israel will be looking for establishment of a nuclear-free zone in the Middle East," Mr ElBaradei said.
BBC diplomatic correspondent Jonathan Marcus says the UN official is keen to convince the Israelis that the best way to avoid further nuclear proliferation in the region is for all governments to join in a collective ban on nuclear weapons.
But the uncertainty surrounding Iran's nuclear ambitions will only serve to confirm the Israeli government's long-held view that a nuclear deterrent is essential to guarantee Israel's long-term security.
Mr Sharon was expected to raise the subject of Iran's nuclear programme at the meeting.
Unlike Iran - which denies it is trying to make nuclear bombs - Israel has not signed the Nuclear Non-proliferation Treaty, which means the International Atomic Energy Agency does not have the power to inspect Israeli nuclear facilities.
The Israelis say that will not change as long as they feel threatened by countries in the Middle East.
Officials have told Mr ElBaradei their main concern is Iran's alleged efforts to make nuclear bombs - something they say threatens their existence.
Mr ElBaradei has been telling Israel that Iran and Arab states see Israel as the main threat - an unaccountable nuclear power that gets special treatment.
He says the perceived security imbalance is wearing down the legitimacy of the non-proliferation regime.
Israel refuses to say whether it has nuclear weapons, although it is thought to have up to 200 warheads.
Mr Sharon has already said he has no intention of changing Israel's policy of "strategic ambiguity".
Our correspondent says that when compared with India and Pakistan, other states which have recently developed nuclear arms, Israel's deterrent is probably the most sophisticated.
It can be delivered by long-range ballistic missiles or advanced war planes, he says.