UNITED NATIONS — Echoing Iran’s threat to wipe Israel off the map, the leader of Hezbollah said yesterday that his organization’s targeting of civilian centers has made it possible for the Jewish state to be “eliminated.”

Threats against Israel from Iranian-backed organizations — Hezbollah in Lebanon and Hamas in Gaza — should not be taken “lightly,” Israeli and American officials said. Israeli military and civilian alert levels were raised in the aftermath of Sheik Hassan Nasrallah’s speech yesterday, delivered 40 days after the killing in Damascus of Hezbollah’s operations commander, Imad Mughniyeh, which Arab leaders have blamed on Israel.

“There is evidence that Hamas is supported by Iran and Syria, and they are doing everything they can to torpedo the peace process,” Vice President Cheney, who met yesterday with Prime Minister Olmert before leaving Israel for Turkey, said.

Hamas and Hezbollah “are betting on Iran as a broker bets on a hot stock,” a former official in the Israeli Foreign Ministry, Jonathan Dahoah Halevi, said. “People in the region assume that as soon as Iran gets a nuclear bomb it will become a regional superpower, which makes it a hot commodity.” Both Jerusalem and Washington have ruled out dealing with Hamas, and officials of the American-backed, Fatah-led Palestinian Authority scrambled yesterday to distance themselves from a reported pact between Fatah and Hamas. The authority’s chief peace negotiator, Ahmed Qurei, told the Israeli Web site Ynet that the Fatah official who signed an agreement in Yemen over the weekend to begin negotiations with Hamas, Azam al-Ahmed, was not authorized to do so by President Abbas.

Sheik Nasrallah said yesterday that Hezbollah changed the regional balance of power with Israel’s 2000 withdrawal from Lebanon, which many in the region saw as a victory for the organization over the strongest army in the region. “Until then, there were those who said that whoever fights the Zionists is crazy,” he said.

The Hezbollah leader addressed a crowd of thousands in his Beirut stronghold, Dahyieh, appearing from an undisclosed location on large video screens. Since Hezbollah proved fighting Israel was possible, the question has been, “Can you end this entity?” he told the crowd.

In the 2006 Hezbollah-Israel war, he added, Israelis could not withstand the bombing of their cities. “Let them be frightened and worried. Let them taste the fear and fright which they inflicted on our people,” he said. “Can Israel be eliminated? Yes and a thousand yeses, Israel can be eliminated.”

“This subject of the intention to attack Israel in the wake of Mughniyeh’s death isn’t something we should take lightly,” Israel’s defense minister, Ehud Barak, said yesterday in a statement.

Arab leaders, meanwhile, who are expected to meet in Damascus for an Arab League summit over the weekend, also are concerned about the rise of organizations like Hezbollah, Hamas, and others who use images of suffering Palestinian Arabs to promote a pan-Islamic caliphate that would replace established states, Mr. Dahoah Halevi said. “In the past, the plight of Palestinians was used as a tail to be wagged by the Arab leaders, who were top dogs,” he said. “Now the Palestinian tail wags the dog.”