Any decision by Israel about a pre-emptive strike on Iran's nuclear facilities remains "very far away," Defence Minister Ehud Barak said on Wednesday as tension rose between Iran and the West.

"We don't have a decision to go forward with these things. We don't have a decision or a date for taking such a decision. This whole thing is very far away," Barak told army radio.

Washington has been spearheading a campaign for much tougher sanctions against the Iranian economy in a bid to rein in a nuclear drive that Israel and many Western governments believe is aimed at developing atomic weapons.

But Israel does not believe Iran has yet taken the decision to begin producing a nuclear warhead, Barak said.

"The Iranians have not ended the oversight exercised by the International Atomic Energy Agency," he said.

"They haven't done that because they know it would constitute proof of the military nature of their nuclear programme and that would provoke stronger international sanctions or other types of action against their country."

Israel, which has the Middle East's sole if undeclared nuclear arsenal, has said an Iranian nuclear weapons capability would pose an intolerable threat to the Jewish state, and has not ruled out military action to prevent it from becoming a reality.

But Russian Foreign Minister Sergei Lavrov warned any strike on Iran would be a "catastrophe" which would have the "severest consequences."

"As for the chances of this catastrophe happening, you would have to ask those constantly mentioning it as an option that remains on the table," Lavrov said.

Reports have suggested a divide between Israel and Washington on the question of military action against Iran, with the United States reportedly pressuring the Jewish state to hold back.

But Barak, speaking on the eve of a visit by top US military chief Martin Dempsey, denied Israel was facing US pressure.

"The chairman of the joint chiefs of staff is not coming with a view to putting pressure of the state of Israel," he said.

"The United States knows that Israel takes American considerations into account, but the Israeli government... (is) responsible for the security of the state of Israel and we cannot set aside this responsibility for anyone, including our American friends."

On Sunday, Israel announced that a major joint exercise with US troops which was due to take place in the spring was being delayed until later in the year.

Israeli officials blamed the postponement on fears it could further ramp up tensions in the region.

Washington has pushed for tough sanctions on Iran, targeting its oil exports and financial institutions, but Israeli Prime Minister Benjamin Netanyahu said this week that the current regime of sanctions was not enough.

Barak said he was happy to see tougher measures being considered, but agreed the current punitive measures would not be enough to compel "the extremist regime in power in Iran to renounce its nuclear activities."

Washington has a longstanding ban on Iranian oil imports and last year barred any firms working with Iran's central bank, which clears its oil receipts, from working with the US financial sector.

And the European Union is mulling phasing in an oil embargo that could go into full force by July.

Iran says its nuclear programme is for peaceful purposes only and has threatened to close the Strait of Hormuz, the strategic waterway for much of the Middle East's oil, if the West presses ahead with sanctions on crude exports.

Meanwhile, Saudi's former intelligence chief warned the kingdom would use "all available options" to defend itself against Iranian "threats."

"Any threat to our interests or security will force us to use all available options to defend our interests, and national and regional security," Prince Turki al-Faisal told a security conference late on Tuesday.

"Iran must not fuel this conflict and must not threaten us," he said.

And Iran's Foreign Minister Ali Akbar Salehi said a new round of talks with the major world powers over his country's nuclear programme were likely to take place in Istanbul -- where the previous negotiations collapsed exactly a year ago.

He was speaking in Ankara where he is to hold talks with Turkey's leaders likely to which were expected to focus on the nuclear issue, officials said.

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