Israel's Prime Minister called off his trip to Washington next week to attend a conference on the spread of nuclear weapons, officials in his office said, fearing Israel would be singled out over its own nuclear program.

Benjamin Netanyahu had said he would attend the conference to underline the dangers of terrorists acquiring nuclear weapons, but suddenly called off the trip less than two days after he announced he would take part.

Officials in his office said early Friday that Netanyahu reversed himself because some nations planned to use the conference to target Israel over its barely concealed nuclear weapons program. The officials spoke on condition of anonymity because no announcement has been made.

In Washington, National Security Council spokesman Mike Hammer confirmed that Israel had informed the U.S. that Netanyahu would be staying home, sending his deputy, Dan Meridor, instead.

The Israeli officials did not name the states thought to be planning to single out Israel, which has not signed the nuclear nonproliferation treaty. Muslim nations _ including Egypt, which has a peace treaty with Israel _ have often complained about Israel's nuclear program.

Israel has not admitted to possessing nuclear weapons, preferring a policy it calls "ambiguity." Based on evidence, international experts have estimated that Israel has dozens, possibly hundreds, of nuclear bombs.

The most detailed evidence emerged in 1986, when a former technician at Israel's main nuclear facility leaked pictures and information to the London Sunday Times. The technician, Mordechai Vanunu, was captured and served an 18-year prison sentence in Israel.

Announcing his intention to fly to Washington, Netanyahu told a Jerusalem news conference on Wednesday that he did not expect pressure over Israel's nuclear program there.

"I'm not concerned that anyone would think that Israel is a terrorist regime," Netanyahu said. "Everybody knows a terrorist and rogue regime when they see one, and believe me, they see quite a few around Israel."

For years, Netanyahu has been leading a campaign to publicize Iran's nuclear program, charging that it is meant to produce nuclear weapons. Israel has called for stiff sanctions against Iran, but at the same time has not taken the option of a military strike against Iranian nuclear facilities off the table.

Israel considers Iran a strategic threat because of its nuclear program, ballistic missiles and repeated references by its president, Mahmoud Ahmadinejad, to Israel's destruction. Iran insists its nuclear program is peaceful.

Netanyahu had hoped to press his case against Iran at the Washington conference.

Beginning on Monday, government leaders from more than 40 countries will gather to discuss improving safeguards against terrorists acquiring nuclear weapons.

Ahead of the conference, the White House announced a major shift in U.S. nuclear policy _ a new focus on the threat of nuclear weapons in the hands of terrorists and rogue regimes rather than on the long-running arms race with Russia.

Netanyahu said Wednesday that it was a "welcome change" that the U.S. and other countries would be discussing the danger that "nuclear weapons, even crude nuclear weapons, would find their way into the hands of terrorists."

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Associated Press Writer Steve R. Hurst in Washington contributed this report.