By Louis Charbonneau

UNITED NATIONS (Reuters) - Israeli Prime Minister Benjamin Netanyahu thanked the United States for blocking an Egyptian-led drive on a possible Middle East nuclear weapons ban at a major United Nations conference, an Israeli official said on Saturday.

It was a rare expression of diplomatic harmony with the United States from Netanyahu, whose relations with President Barack Obama have been strained over U.S.-led nuclear talks with Iran and differences over Israeli-Palestinian diplomacy.

A month-long conference on the 1970 nuclear Non-Proliferation Treaty (NPT) ended in failure on Friday over disagreements on how to achieve a Middle East atomic weapons ban. Washington blamed the failure on Egypt, which in turn blamed the U.S., British and Canadian delegations.

Netanyahu conveyed his gratitude to President Barack Obama and Secretary of State John Kerry in a call to Kerry, said a senior Israeli official, requesting anonymity.

"The United States kept its commitment to Israel by preventing a Middle East resolution that would single out Israel and ignore its security interests and the threats posed to it by an increasingly turbulent Middle East," the official said.

Israel also thanked Britain and Canada for joining the United States in blocking consensus, the official said.

U.N. Secretary-General Ban Ki-moon voiced disappointment that NPT parties were "unable to narrow their differences on the future of nuclear disarmament or to arrive at a new collective vision on how to achieve a Middle East zone free of nuclear weapons and all other weapons of mass destruction (WMD)."

Last month, Egypt, backed by other Arab and non-aligned states, proposed that Ban convene a regional conference on banning WMD as called for at the 2010 NPT review meeting. A planned 2012 conference on the issue never took place.

According to Egypt's proposal, that conference could take place with or without Israel's participation, and could be held without agreement on an agenda or discussion of regional security issues - two of Israel's conditions for participating.

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Israel neither confirms nor denies the widespread assumption that it controls the Middle East's only nuclear arsenal. Israel, which has never joined the NPT, agreed to take part in the review meeting as an observer, ending a 20-year absence.

Egypt's proposals, Western diplomats say, were aimed at pressuring Israel. Washington and Israel say Iran's nuclear program is the real regional threat.

Iran says its program is peaceful. It is negotiating with world powers to curb it in exchange for lifting sanctions.

Israel has said it would consider joining the NPT only once at peace with its Arab neighbors and Iran.

(Reporting by Matt Spetalnick in Washington; Editing by Robin Pomeroy and Dan Grebler)