Secretary of State Hillary Rodham Clinton will try this week at the United Nations to keep the worst-kept secret in the Middle East: Israel's status as a nuclear power.

In recent weeks, the U.S. government has held talks with Egypt on a proposal to eliminate nuclear weapons in the Middle East. The U.S. diplomacy on the proposal also has been coordinated closely with Israel, according to a senior White House official.

That proposal is likely to be a major point of debate this month at the review conference for the nuclear Non-Proliferation Treaty (NPT) that is set to begin in New York on Monday. Mrs. Clinton is leading the U.S. delegation to the opening of the conference.

The United States is trying to rally the U.N. Security Council to pass a fourth resolution to sanction Iran's nuclear program. The conference will focus on ways to strengthen the fraying treaty and isolate Iran, U.S. officials said.

Iranian President Mahmoud Ahmadinejad will attend the conference as the head of his country's delegation. He is expected to raise the issue of Israel's nuclear weapons to deflect attention from Iran's enrichment of uranium.

Iran could have an ally in traditional rival Egypt, whose delegation will be pushing for a resolution that would have the effect of singling out Israel, one of the three countries in the world that has never signed the NPT.

As an undeclared nuclear power, the Israeli government does not confirm that it has nuclear weapons. It is illegal in Israel for newspapers to print that the country has nuclear arms.

For 40 years, the United States has been a partner in Israel's nuclear opacity as well. In a deal fashioned in 1969 between President Nixon and Israeli Prime Minister Golda Meir, the United States does not pressure Israel to join the treaty, which would require the Jewish state to give up its nuclear weapons. Israel, in turn, does not acknowledge it has the weapons.

The Egyptian working paper of March 2010 on the nuclear-free Middle East threatens to upset this secret understanding. Specifically, it would require member states of the NPT to "disclose in their national reports on the implementation of the resolution on the Middle East all information available to them on the nature and scope of Israeli nuclear facilities and activities, including information pertaining to previous nuclear transfers to Israel."

The Egyptian working paper also calls for a conference by 2011 on making the Middle East free of nuclear weapons and a special envoy to coordinate such a conference.

Speaking to reporters Friday, Ellen Tauscher, undersecretary of state for international security and arms control, said the United States supports in principle the long-term goal of a nuclear-free Middle East.

But she said that a conference on this issue should follow a comprehensive peace in the region and should address weapons of mass destruction programs in addition to nuclear weapons.

"We believe that this is a very worthy goal, something that we have supported since 1995," Ms. Tauscher said. "But we are concerned that the conditions are not right. And unless all members of the region participate, which would be unlikely unless there is a comprehensive peace plan that is being accepted and worked on, then you couldn't have the conference that would achieve what we are all looking to achieve, which is for the region to make its own decisions and come together and find a way to do that."

Ms. Tauscher's position is substantively no different from the secret Israeli strategic doctrine known as the "long corridor," which establishes conditions — such as peace agreements with its neighbors — for Israel to relinquish its nuclear weapons.

The official Israeli statement, for example, from the International Atomic Energy Agency conference in September endorsed the long-term goal of a nuclear-free Middle East.

It also said, "in our view, progress towards realizing this vision cannot be made without a fundamental change in regional circumstances, including a significant transformation in the attitude of states in the region towards Israel."

An Israeli official said Sunday: "We haven't changed our policy. We are in favor of and support a nuclear-free Middle East. We believe this should be a culmination of a process and not the beginning of a process, this is a process that includes individual and bilateral peace agreements."

At last year's U.N. General Assembly, Prime Minister Benjamin Netanyahu said he sought and received assurances from President Obama on a series of strategic understandings between the two countries. The Washington Times first reported last year that one of those reassurances was the Meir-Nixon understanding.

Over the weekend, U.S. officials tried to lower expectations that Egypt would modify its proposal for a nuclear-free Middle East. "We are still in the early stages of negotiations," a senior White House official said.

One possible compromise would be for the United States to accept naming an envoy or coordinator for a regional conference on seeking a Middle East that is free of weapons of mass destruction.

"It appears that the various key players could reach agreement in principle to name a special envoy and to call upon states in the region to meet to discuss the issue," said Daryl Kimball, executive director of the Arms Control Association. "This is a helpful, country-neutral way to deal with the Iranian issue and Israel's controversial nuclear program."

David Albright, president of the Institute for Science and International Security, said a deal with the Egyptians is within reach.

"The key is for the U.S. administration to quietly let the Egyptians know that at the presidential and vice-presidential level, the United States takes the issue of a WMD-free zone in the Middle East seriously."

On April 13, Vice President Joseph R. Biden Jr. met with Egyptian Foreign Minister Ahmed Aboul Gheit and other foreign ministers during the summit on uncontrolled nuclear material.

A senior administration official said, "At the lunch, they discussed the NPT and how to strengthen it."