A top US security official met Israeli Prime Minister Benjamin Netanyahu on Sunday amid rising concerns over Iran and ahead of a trip by the Israeli premier to Washington.

Public radio said he and US National Security Advisor Tom Donilon had a two-hour meeting that focused on "regional threats," despite Netanyahu's office refusing to confirm any meeting or to comment.

The White House had said Donilon would discuss a range of issues with senior Israeli officials, including Syria, and an Israeli official had said he would meet Netanyahu on Sunday afternoon.

The visit comes at a time of heightened tension between Israel and Iran over Tehran's nuclear programme, and after attacks on Israeli diplomats blamed on agents of Tehran.

In recent weeks, there has been feverish speculation that Israel was getting closer to mounting a pre-emptive strike on Iran's nuclear programme, though Israel has denied reaching such a decision.

Tensions between Iran and Israel also have been simmering with Iranian warships entering the Mediterranean in a show of "might," a move Israel said it would closely monitor.

Netanyahu said at Sunday's weekly cabinet meeting that on the agenda was a review by defence officials of the state of Israel's civil defence readiness.

"This is part of continuous action we have been taking in recent years in order to prepare Israel for the new age," he said. "An age of threats to the Israeli home front." He did not elaborate.

On Sunday night, Netanyahu spoke to a conference of the presidents of Jewish American organisations, and said Israel faced "four threats."

"The first is nuclear, the second is missiles with many thousands aimed at Israel and its cities, the third is cyber attacks, the fourth is border infiltration not only by terrorists, but by mainly foreigners who threaten the Jewish nature of our small state."

A military spokesman said on Sunday that a battery of rocket interceptors from its "Iron Dome" system would be deployed in the Tel Aviv area from Monday.

Designed to intercept rockets and artillery shells fired from a range of between four and 70 kilometres (three and 45 miles), Iron Dome is part of an ambitious multi-layered defence programme to protect Israeli towns and cities.

Israeli media on Sunday quoted a CNN interview with the chairman of the US Joint Chiefs of Staff, General Martin Dempsey, warning that an Israeli military strike on Iran would be "destabilising."

"Its not prudent at this point to decide to attack Iran," the Jerusalem Post quoted him as saying in a transcript of the interview.

"The US government is confident that the Israelis understand our concerns," it quoted Dempsey as saying.

"A strike at this time would be destabilising and wouldnt achieve (Israel's) long-term objectives."

Israel's former national security adviser Uzi Dayan called Dempsey's choice of words significant.

"I would emphasise Martin Dempsey's use of the phrase 'at this point'," he told public radio, pointing to Iran's latest offer to resume stalled nuclear talks with the five permanent UN Security Council members -- the United States, Russia, China, France and Britain -- plus Germany.

The United States, other Western powers and Israel believe that Iran is seeking to build a nuclear bomb, but Tehran denies the charge, insisting its atomic programme is for purely peaceful purposes.

Israel is widely believed to be the sole nuclear-armed power in the Middle East, albeit undeclared.

Donilon's visit comes ahead of a trip in early March by Netanyahu to Washington for talks with US President Barack Obama which are likely to focus on Iran and stalled peace talks between Israeli and Palestinian negotiators.

Top-selling Israeli daily Yediot Aharonot said on Sunday that US Director of National Intelligence James Clapper would visit Israel later in the week for talks with defence and intelligence officials.

Both Clapper and Donilon "plan to deliver a calming message, that even if talks are resumed with Iran, this will not be at the expense of the sanctions, which will continue to mount unless Iran puts an immediate halt to its nuclear programme and allows serious supervision," the paper said.

It added that Defence Minister Ehud Barak would make a preparatory trip to Washington ahead of Netanyahu.

Top US aide heads to Israel for talks on Iran, Syria
Washington (AFP) Feb 18, 2012 - US National Security Advisor Tom Donilon will travel to Israel on Saturday for talks with senior Israeli officials on a range of issues, including Iran and Syria, the White House announced.

The announcement came as US Secretary of State Hillary Clinton and EU foreign policy chief Catherine Ashton voiced cautious optimism about the prospect for Iran to return to nuclear talks with six world powers.

The top White House aide's visit "is the latest in a series of regular, high-level consultations between the United States and Israel, consistent with our strong bilateral partnership, and part of our unshakable commitment to Israel's security," a White House statement said.

The move comes at a time of heightened tension between Israel and Iran, in the wake of attacks on Israeli diplomats blamed on agents of Tehran.

The visit comes ahead of a visit to Washington by Israeli Prime Minister Benjamin Netanyahu for White House talks with Obama in early March, where the leaders are likely to focus on Iran and the failure to find a deal on resuming direct talks between Israeli and Palestinian negotiators.

Meanwhile, during a press conference in Washington with Ashton, Clinton called a letter that the European Union's top diplomat had received from Iran "an important step" after a year-long hiatus in negotiations and sharp tension.

"There is a potential possibility that Iran may be ready to start talks. We'll continue to discuss and make sure that what we're looking at is substantive," Ashton said at a press conference with Clinton.

"But I'm cautious and optimistic at the same time for this," she added as US officials have suggested that the economic bite of sanctions may be pressing Iran to return to the negotiating table.

In a February 14 letter to Ashton, Iran's chief nuclear negotiator Saeed Jalili said Tehran is ready to resume stalled nuclear talks at the "earliest" opportunity as long as the six powers respect its right to peaceful atomic energy.

Ashton represents the permanent five UN Security Council members -- the United States, Russia, China, France and Britain -- plus Germany in talks with Iran.

Ashton had written in her letter to Jalili in October that a solution was possible only if the talks focused on addressing Western concerns over the nature of Iran's nuclear program.

Clinton, while stressing the six powers needed more time to study the brief letter, noted some positive signs.

"I think it's fair to say... that we think that this is an important step and we welcome the letter," the chief US diplomat said.

"As outlined in Cathy's October letter to Iran, any conversation with Iran has to begin with a discussion of its nuclear program and Iran's response to Cathy's letter does appear to acknowledge and accept that," Clinton said.

Jalili wrote that Iran welcomed a statement in the letter "respecting Islamic Republic of Iran's right to the peaceful use of nuclear energy consistent with the NPT (nuclear non-proliferation treaty)."

"No doubt that by committing to this approach, our talks for cooperation based on step by step principles and reciprocity on Iran's nuclear issue could be commenced," Jalili wrote.

Ashton acknowledged that the letter contained "no preconditions and a recognition of what we'll be talking about."

Clinton spokeswoman Victoria Nuland cautioned against any more "false starts" in negotiations with the Iranians.

"We've had negotiations that started and fizzled, or negotiations that ate up a lot of time and didn't go where they needed to go to reassure the international community," Nuland told reporters.

The last round of talks collapsed in Turkey in January 2011.

"The next question, really, is to look at then where we left off in Istanbul," Ashton said, recalling that the powers had outlined confidence-building steps such as ensuring freer movement for inspectors.

The United States and other Western powers suspect that Iran is seeking to build a nuclear bomb, but Tehran denies the charge, insisting its atomic program is for purely peaceful purposes.

In a dual-track strategy, the six powers have offered Iran economic and diplomatic incentives to engage in negotiations to stop uranium enrichment work or pushed for imposing biting sanctions when they refuse.