Israel is extremely concerned about Iran's nuclear ambitions, the head of the U.N. atomic watchdog agency said Wednesday, an indication that the issue is preventing any change in Israel's nuclear policy.

"They're expressing concern about Iran," Mohamed ElBaradei (search), director general of the International Atomic Energy Agency (search), said after talks with senior officials at Israel's secretive nuclear energy agency.

ElBaradei arrived in Israel on Tuesday to pitch for a Middle East free of nuclear weapons. Israel refuses to discuss its nuclear capacities, but it is thought to be the only state in the Middle East possessing nuclear weapons.

Later Wednesday, ElBaradei was scheduled to meet with the Israeli health minister and take an aerial tour over the country.

While declining to go into details about his talks, ElBaradei indicated Wednesday that fear that Tehran was trying to develop nuclear arms was a dominant theme.

ElBaradei's agency is probing nearly two decades of suspect nuclear activities in Iran that the United States, Israel and others say reflect attempts to make such weapons.

Tehran insists it only wants nuclear energy to generate power, but several IAEA reports over the past year have suggested the Islamic Republic has not fully cooperated with agency inspectors and has failed to clear up suspicions about its aims.

ElBaradei has suggested that the Israelis should at least consider loosening their taboo on talking about nuclear arms as part of any long-term Middle East settlement that would rid the region of such weapons.

He acknowledged Tuesday that he had no "magic wand" to change Israel's policy of so-called nuclear ambiguity.

"But in the long run you need to build a system, where nuclear weapons and other weapons of mass destruction will not be part of your security structure," he said.

In Washington, Secretary of State Colin Powell declined to take a stand Tuesday on whether Israel should be forced to open its reactors to inspection.

But Powell, at a joint news conference with Israeli Foreign Minister Silvan Shalom (search), renewed his demand for international pressure on Iran to stop what Washington says are attempts to build nuclear arms.

Earlier Tuesday, Israel Army Radio rebroadcast comments made in May by Prime Minister Ariel Sharon, who said he would not budge from the country's traditional "no show, no tell" policy.

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

Israel's doctrine of nuclear ambiguity is meant to deter its enemies, while denying them the rationale for developing their own nuclear weapons.

While ElBaradei was scheduled to meet Sharon Thursday, there were no plans to give him access to Israel's main nuclear facility near Dimona (search) in the southern Negev Desert, which is the suspected center of its nuclear weapons program.

Israel has not signed the Nuclear Nonproliferation Treaty (search), which would force it to declare itself a weapons state and curb its nuclear activities.

But ElBaradei said he hoped to persuade Israeli leaders to agree to a separate protocol curbing nuclear exports and imports.

Such a move would be mostly symbolic — Israel already has strict export and import commitments — and is seen as an attempt to nudge it toward increased cooperation with the IAEA.

Evidence 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), as well as research and statements made by Israeli leaders.

Vanunu, who was freed in April after serving an 18-year sentence for espionage and treason, urged ElBaradei to persuade Israeli leaders to allow him into the Dimona plant.

"Now, after 18 years that my revelation has gone to all the world and I come out of prison and report to all the world, he too must go and demand to be inside Dimona and to report to IAEA and to all the world," Vanunu said on Israel's Channel One TV, in only his second interview since his release from prison.

Israel is believed to be the only country in the region to have nuclear missiles ready to launch. Experts say it may already have as many as 300 warheads as well as the capability of building more quickly.