Mitt Romney, the Republican candidate in the US presidential election, would respect an Israeli decision to use military force to stop Iran from developing a nuclear weapon, a senior aide said yesterday.

Mr Romney met Israeli Prime Minister Benjamin Netanyahu in Jerusalem on the second leg of a foreign trip aimed at bolstering his foreign policy credentials.

His aim is to garner the pro-Israel vote and carry sufficient authority to unseat President Barack Obama in the November poll.

Shortly before the talks, Mr Romney's leading national security aide, Dan Senor, said: "If Israel has to take action on its own to stop Iran from developing that capability, the governor would respect that decision."

The comment seemed to put Mr Romney at odds with Mr Obama's efforts to press Israel to avoid any pre-emptive strike before Western economic sanctions against Iran run their course.

Mr Senor later expanded on his remarks, saying Mr Romney felt "we should employ any and all measures to dissuade the Iranian regime from its nuclear course".

It was Mr Romney's "fervent hope that diplomatic and economic measures will do so," and "no option should be excluded", said Mr Senor, who added that "Romney recognises Israel's right to defend itself, and that it is right for America to stand with it".

Standing beside Mr Netanyahu at the Israeli leader's office, Mr Romney said only that Iran's effort to become a nuclear power "is one which I take with great seriousness".

The failure of talks between Iran and six world powers to secure a breakthrough in curbing what the West fears is a drive to develop nuclear weapons has raised international concern Israel may opt for a go-it-alone military strike.

Mr Netanyahu issued a call for stronger measures behind the sanctions to curb Iran's atomic ambitions, which Israel sees as a threat to its existence. Iran has continually stated the programme is solely for peaceful purposes.

Mr Netanyahu said: "Sanctions have not set back the Tehran programme one iota. A strong military threat, coupled with sanctions, is needed to have a chance to change the situation."

Israel has warned it is only a matter of time before Iran's atomic programme achieves a "zone of immunity" in which bombs will not be able to effectively strike uranium enrichment facilities deep underground.

Mr Romney has criticised Mr Obama's handling of Iran as not being tough enough.

Though Washington has been pressing Israel not to launch a solo strike on Iran, Mr Obama has not ruled out military action if diplomacy fails to curb Iran's nuclear drive.

The Israeli newspaper Haaretz said yesterday Mr Obama's national security adviser had briefed Mr Netanyahu on a US contingency plan to attack Iran.

An Israeli official denied the claim.