Israel's Defence Minister Ehud Barak issued a stark warning last night that military action may be needed to prevent Iran acquiring nuclear weapons before it is "too late" and Tehran puts its programme beyond the reach of external attack.

Mr Barak insisted that despite "disagreements among us", the world had no doubt that Iran's nuclear programme was "slowly but surely" reaching the final stages before it would be "able to complete such a programme without any effective intervention".

He declared to the annual gathering in Herzliya of the country's security establishment: "Many experts in the world believe that refraining from action will necessarily mean dealing with a nuclearised Iran." This "will be far more complex, far more dangerous and far more costly in blood and money than stopping it today... Those who say 'later' may find that later is too late."

Mr Barak said the latest tightening of sanctions against Iran was a "step in the right direction" and "must be intensified until the goal is attained to stop the programme". But he then declared: "If the sanctions do not achieve the desired effect of stopping the military nuclearisation programme, action must also be considered."

The Defence Minister's remarks came as US Defence Secretary Leon Panetta declined to deny a report in the Washington Post that he feared a military strike on Iran by Israel during April, May or June. Mr Panetta said the US had indicated its "concerns" about a possible Israeli attack.

Mr Barak was not specific when he spoke about the differences of view. But earlier yesterday, Ephraim Halevy, a former head of Mossad, took an upbeat view of the capacity of present sanctions to bite.

Mr Halevy said the depreciation by 50 per cent of the Iranian rial, a run on the banks and "rocketing sky high food prices" was why "Iran has done what it swore it would never do and put the nuclear issue on the agenda of discourse between Iran and the world".

Deputy Prime Minister Moshe Yaalon said a military base near Tehran was "preparing to produce or develop a missile with a range of 10,000km... aimed at the 'Great Satan', the United States of America, and not us."