In his pitch for a Middle East free of nuclear weapons, the head of the U.N. atomic watchdog agency is likely this week to press for at least tacit acknowledgment from Israel that it has such arms or the means to make them.

Israeli does not directly comment on its nuclear capacity, and the International Atomic Energy Agency (search) will not specify how hard IAEA head Mohamed ElBaradei (search) will push officials during his two-day visit to Israel starting Tuesday.

But ahead of the trip ElBaradei has said that Israel should start talking seriously about a nuclear arms-free Middle East whether or not it owes up to owning them. Earlier this year, he condemned the imbalance caused in the Middle East because of "Israel sitting on nuclear weapons."

On the eve of ElBaradei's trip, IAEA spokesman Mark Gwozcecky linked it to the need "for a strategic dialogue at nuclear issues, aimed at building up ... mutual confidence, and in the long run, making the region free of weapons of mass destruction."

Still, senior diplomats familiar with the Vienna-based IAEA and the purpose of ElBaradei's visit said they did not expect it to change Israel's "no show, no tell" policy, particularly at a time of fears that Iran, Israel's foe, is secretly trying to develop such weapons.

Reflecting Israel's continued policy of keeping the agency at arm's length, they said ElBaradei would not be visiting Dimona (search), the nuclear facility thought to be at the heart of Israel's weapons program.

ElBaradei was to meet Prime Minister Ariel Sharon (search) and other senior officials. Still, Israeli analysts warned against even low expectations.

"There is no foundation for a change in Israel's policy of nuclear ambiguity under present circumstances, and the topic is not on the agenda," wrote Gerald M. Steinberg, a fellow at the Jerusalem Center for Public Affairs (search).

On Tuesday, Israel's Army Radio quoted Sharon as saying Israel would not change its "no show, now tell" policy, and that he would ensure the country had all the necessary weapons to protect itself.

"I don't know what he is coming to see. Israel has to hold in its hand all the elements of power necessary to protect itself by itself," Sharon was quoted as saying. "Our nuclear policy has proven itself and will continue."

Evidence that that Israel has nuclear arms is overwhelming, much of it based on details and pictures leaked in 1986 by Israeli nuclear technician Mordechai Vanunu (search), other leaks, research — and on statements made by Israeli leaders.

"Give me peace, and we will give up the atom," declared Israeli Prime Minister Shimon Peres (search) in 1995, when hopes for a Middle East settlement were still alive. "If we achieve regional peace, I think we can make the Middle East free of any nuclear threat."

Israel's doctrine of "nuclear ambiguity" — never formally confirming or denying that it has such weapons — is meant to keep the Islamic world from considering an annihilating attack while denying it the rationale for developing its own nuclear deterrent.

While the United States accuses Iran and possibly Syria of interest in such weapons, Israel is believed far advanced and the only country in the region thought to have nuclear missiles ready to launch.

Still, Israel has left few footprints in developing any weapons program. And because it has resisted international pressure to sign the Nuclear Nonproliferation Treaty (search), Israel does not formally have to declare itself as a weapons state or agree to any curbs on its nuclear activities.

That leaves the IAEA and the rest of the world guessing about the nature and scope of Israel's program.

Experts say Israel may already have as many as 300 warheads as well as the capability of building more quickly.

David Albright, a former Iraq nuclear inspector who runs the Washington-based Institute for Science and International Security (search), says that despite turbulence in the Middle East the time might be right for ElBaradei's mission because "Iraq has been dealt with" as a threat to Israel, and "Iran is being isolated" as the world pushes for exposure of its nuclear secrets.

Nuclear expert Avner Cohen, a senior fellow at The University of Maryland, says Israel's policy has served it well by acting as a deterrent while denying enemies the chance of arguing they have the right to nuclear weapons as well. But he says "opacity" has outlived its usefulness and Israel should now be up front about its capacities.