An Israeli attack on Iran's nuclear programme could trigger a bloody month-long war on multiple fronts, killing hundreds of Israelis or more, the Israeli Cabinet's civil defence chief warned yesterday.

It was the most explicit assessment yet of how the Government sees events unfolding following an Israeli attack.

Matan Vilnai, who is stepping down as the "home front" Cabinet minister to become Israel's ambassador to China, described the scenarios to Israel's Maariv daily at a time of heightened debate about the Iranian nuclear threat.

Vilnai, a retired general who was deputy military chief of staff, has spent the past five years overseeing upgrades of Israel's civil defence systems, including air-raid sirens, bomb shelters and a public alert system.

In the interview, Vilnai said "the home front is ready as never before".

Nonetheless, he said the country must be braced for heavy casualties in the case of conflict with Iran.

Vilnai said the Government had prepared for the possibility of hundreds of rockets and missiles falling on Israeli population centres each day, with the expectation of 500 deaths.

"It could be that there will be fewer fatalities, but it could be there will be more. That is the scenario that we are preparing for.

"The assessments are for a war that will last 30 days on a number of fronts."

Israel is convinced that arch-enemy Iran is trying to build nuclear weapons, dismissing Tehran's claims that its nuclear programme is for civilian purposes. Israel considers nuclear-armed Iran to be a mortal danger.

Iran backs anti-Israel militants with funds and weapons, and its leaders often call for Israel's destruction.

In his latest pronouncement, Iranian Supreme leader Ali Khamenei said Israel will disappear from "the scene of geography". Addressing war veterans in Tehran, he said Iran considers it its "religious duty to save this Islamic country [Palestinian territories] from the clutches of the Zionist occupiers."

Israel's leaders have indicated an attack is a possibility if they conclude that the international community has failed to halt the Iranian nuclear programme.

Defence Minister Ehud Barak has also said the Israeli death toll could be in the range of 500 in such a conflict.

"Just as the citizens of Japan have to realise that they can have earthquakes, so the citizens of Israel have to realise that if they live here, they have to be prepared to expect missiles on the home front," Vilnai said. "We have to be ready."

At a news briefing in Washington yesterday, US Defence Secretary Leon Panetta reaffirmed the US assessment that Israel had not yet decided whether to strike, while the US military chief, General Martin Dempsey, echoed a widely held assessment that an Israeli operation would only set back, not destroy, Iran's nuclear project.

The Israeli public appears to be largely taking the war talk in its stride, in part because some suspect Israel's leaders are essentially bluffing in order to compel the world to get serious about the issue. But there is a growing sense of foreboding.

Never in Israel's history has there been so much talk about an impending war, security affairs analyst and Iran expert Yossi Melman wrote in a column on the Walla! news website this week.

"It's one thing for the media to blather about it, but why are leaders and senior officials chattering themselves to death?" he asked.

The Iranian threat, Prime Minister Benjamin Netanyahu said this week, "dwarfs any challenge the Israeli home front faces".

The Israeli media have been filled with leaked reports attributable to senior officials projecting a sense that patience is growing thin: The sanctions don't go far enough, and although they have fuelled inflation and hammered the standard of living in Iran, they fall short, especially because Russia and China notably refuse to fall into line.

Hints dropped privately by senior officials and multiple warnings by Israeli leaders about time growing short have created the impression that Netanyahu and Barak have given up on the idea of pressuring Iran through economic and diplomatic sanctions, and are out to attack by the early northern autumn unless Iran abandons its uranium enrichment programme.

Melman wrote: "The hot topic on the Israeli street is when will the war break out and where to take cover in the event of a missile attack." AP

By Amy Teibel