Israel is reported to be seeking to extend the range of its Jericho- 3 ballistic missile, which could be used for pre-emptive military strikes against Iran's nuclear facilities.

Amid persistent concerns that Israel may launch unilateral attacks, Israeli Prime Minister Binyamin Netanyahu, a hawk on the issue, warned Monday that a nuclear Iran will pose a direct threat to Israel.

The Haaretz daily reported Tuesday the Israeli government stepped up its diplomatic campaign for tougher action to force Tehran to abandon its contentious nuclear program.

"Israeli ambassadors in Western countries have been instructed to inform high-ranking politicians that the window of opportunity for imposing effective sanctions on Iran is closing," the newspaper said.

Britain's Guardian newspaper Monday cited a report by the British American Security Information Council that Israel is "extending the Jericho 3 missile's range and developing an ICBM capability by expanding its nuclear-tipped cruise missiles-enabled submarine fleet."

The council, a think tank with offices in London and Washington, deals with global security issues and advocates a nuclear-free world.

The report said the Israeli program was part of an overall effort by the nuclear powers to spend billions of dollars upgrading nuclear warheads and delivery systems over the next decade.

This, the council's report said, pointed to a new and dangerous era of nuclear weapons, with the United States expected to spend $700 billion and Russia to spend $70 billion on delivery systems alone.

Israel and several other countries, including Russia, Pakistan and France, are assigned nuclear weapons roles that go well beyond deterrence, the report observed. It didn't address Iran's nuclear program.

"In the case of Israel, the size of its nuclear-tipped, cruise missile-enabled submarine fleet is being increased and the country seems to be on course, on the back of its satellite launch rocket program, for future development of an intercontinental ballistic missile," the report noted.

It was referring to Israel's Shavit rocket booster used to loft Israeli surveillance satellites into orbit, focused primarily on Iran, which is estimated to have deployed some 200 Shehab-3b ballistic missiles.

These liquid-fueled weapons can reach Israel and are expected to be supplanted by more advanced and more accurate, solid-fueled Sejjil-2 missiles now being developed.

At present these can only carry conventional warheads since, as far as is known, the Iranians haven't been able to produce nuclear warheads.

The Shavit is a version of the Jericho-2 and Jericho-3 ballistic missiles that constitute one element of its strategic nuclear force.

The air force's F-16I and F-15I jets are capable of delivering nuclear bombs, while the navy's expanding fleet of German-built Dolphin class submarines, supposedly capable of launching nuclear cruise missiles, completes the nuclear triad.

Israel has three Dolphins operational, and reportedly keeps one on station in the Arabian or Red seas to cover Iran. It has two more advanced variants on order and these are expected to be delivered 2012-13.

It has ordered a sixth but Berlin is reportedly reluctant to conclude the sale because of Israel's plans to build settlements in East Jerusalem.

It has long been thought likely that ballistic missiles, armed with non-nuclear high-explosive warheads, would be Israel's weapon of choice to hit Iran's nuclear infrastructure.

These would avoid the deployment of the cream of Israel's air force, which isn't considered capable of delivering a knockout blow against Iran's nuclear network on its own, and the high risk of heavy casualties.

Jordanian analyst Abdullah Toukan of the Center for Strategic and International Studies in Washington estimated in a 2009 study that it would take 42 Jerichos to demolish or seriously damage Iran's widely dispersed and heavily protected key nuclear sites, including the uranium enrichment plant outside the central city of Natanz.

Jericho missiles, including Jericho-3s, are deployed in heavily fortified bunkers in the Judean Hills of central Israel, east of Jerusalem. It's not known how many Jericho 2s and 3s the Israelis have and their capabilities are classified.

But Western experts say the three-stage, solid-fuel Jericho 3 has an estimated range of 3,000-4,000 miles. That means Israel can hit targets anywhere in the Middle East, including Iran.

It's believed the missile can carry a 1,650-pound nuclear warhead or two or three low-yield multiple independently targetable re-entry vehicle -- MIRV -- warheads.