Israel is in the sights of the United Nations' nuclear watchdog.

For months Iran has been targeted by Western nations who have threatened sanctions and isolation over its apparent push to build a nuclear bomb.

But Israel is the only country in the Middle East which is believed to already have atomic weapons.

Israel has never signed the Nuclear Non-Proliferation Treaty and now the International Atomic Energy Agency (IAEA) wants Israel's position discussed at a meeting in June.

Israel will never say whether or not it has the nuclear bomb but Western governments have long assumed the Jewish state has a nuclear arsenal at its Dimona plant in the Negev desert, and may have done for 40 years.

Nuclear expert Avner Cohen says Israel is in all likelihood the Middle East's sole, if undeclared, nuclear power.

"The current estimate, in part based on US intelligence, is that Israel probably has a modest arsenal of 80 to 100 weapons, but it's all speculation," he said.

Professor Cohen believes Israel has a unique right to have the nuclear bomb.

"There is a sense that Israel with its own historical legacy, the memory of the Holocaust, deserves to have [a] national insurance policy in the form of nuclear capability, just to ensure that another Holocaust would not happen," he said.

But as speculation mounts about Iran's nuclear program, Arab nations have renewed a push for a Middle East free of nuclear weapons.

They say they want Israel to sign the Nuclear Non-Proliferation Treaty, something Iran has done but Israel has not because to do so would force it to open its nuclear plant for inspection.

Jamil Rabbah, a Palestinian delegate to arms control and regional security talks, voices the views of many Arabs in the region.

"The fact that Israel continues to maintain a nuclear capability in itself is not conducive to reaching some kind of a peace agreement," he said.

Israeli defence minister Ehud Barak says his country's position is correct.

"There's no reason to change it and on this issue we are operating in coordination, I say with the necessary precautions, with close coordination with the United States," he said.

Israel says it would support a nuclear-weapons-free Middle East but only after there is a peace agreement for the entire region.

But some, such as Professor Cohen, believe at the very least Israel can and should end its policy of secrecy.

"I think that Israel would have to find a way to acknowledge it," he said.

"I think that if you want to deal with Iran you need to have this norm of acknowledgement and of transparency."

But with no chance of a change in Israel's nuclear policy, there is now pressure for the UN watchdog to drop Israel from its agenda before next month's meeting.