Melbourne: The United States on Monday rejected Israeli concerns that it had become necessary to pursue a credible military threat against Iran, saying sanctions could deter Tehran from building a nuclear weapon.

The United States fears that Iran's nuclear enrichment programme is aimed at developing atomic weapons, but Tehran says the purpose is to produce fuel for atomic power.

"I disagree that only a credible military threat can get Iran to take the action that it needs to end its nuclear weapons programme," US Defence Secretary Robert Gates told a news conference in Melbourne after security talks with Australia.

"We are prepared to do what is necessary. But at this point we continue to believe that the political, economic approach that we are taking is in fact having an impact in Iran."

Israeli Prime Minister Benjamin Netanyahu told US Vice-President Joe Biden on Sunday that only a credible military threat can deter Iran from building a nuclear weapon, Israeli political sources said.

Measurable impact

Biden said after the talks that the sanctions "have a bite" and were having a "measurable impact", though he expressed frustration that Iran had brushed aside overtures made by President Barack Obama's administration.

Gates said that all options remained on the table.

"The president has said repeatedly that when it comes to Iran that all options are on the table and we are doing what we need to do to ensure that he has those options," he said.

Gates said that tough new sanctions approved by the UN Security Council were "bringing pressure to bear on the Iran government and getting attention".

"We know that they are concerned about the impact of the sanctions. The sanctions are biting more deeply than they anticipated," he said.

Iranian Foreign Minister Manouchehr Mottaki has said Iran is ready to hold talks on its nuclear programme with major powers, and proposed the talks be held in Turkey.

"The Iranians have reached back out and said they would be willing to meet, but so far as I know there is no date or time for that meeting," US Secretary of State Hillary Clinton told the news conference in Melbourne.

"Certainly we have made it clear we would welcome a return to the negotiating table."

Israel's talk of a military threat has raised speculation in Israeli media that Netanyahu, who has rebuffed US and international calls to reimpose a freeze on building in West Bank colonies, was trying to shift the focus of his visit away from the colonies stalemate.

But Netanyahu had made clear that Israel wanted to see if tough economic sanctions could eliminate what it has described as a threat against its existence.

Netanyahu is scheduled to meet Clinton in New York on Thursday for a fuller discussion on Israeli-Palestinian issues. Netanyahu will not see Obama.