US Defense Secretary Robert Gates admitted Sunday sending a memo to the White House in January about Iran's nuclear program but denied a report that it was intended as a "wake-up call."

"The New York Times sources who revealed my January memo to the National Security Advisor mischaracterized its purpose and content," a statement from Gates said.

An unnamed senior official quoted by the newspaper described it as "a wake-up call" that had sparked efforts in the Pentagon, the White House and the intelligence agencies to develop new options for President Barack Obama.

But Gates said it was simply a policy document aimed at laying out defense planning at a time when the Obama administration was looking to begin applying more pressure on Iran over its suspect nuclear activities.

"The memo was not intended as a 'wake up call' or received as such by the president's national security team," Gates said.

"Rather, it presented a number of questions and proposals intended to contribute to an orderly and timely decision making process."

The New York Times said the memo urged the White House to think about how the United States might contain Iran if it decided to produce a weapon and how to deal with the possibility that nuclear fuel or weapons could be obtained by one of the militant groups Iran supports.

Options reportedly included a secret military operation against Iran if international sanctions fail.

Gates dismissed criticism from The New York Times that the three-page memorandum meant Washington lacked an effective long-term strategy for dealing with Iran's alleged nuclear weapons push.

"There should be no confusion by our allies and adversaries that the United States is properly and energetically focused on this question and prepared to act across a board range of contingencies in support of our interests," he said.

Administration critics suggested that the report provided fresh evidence of the Obama administration's rudderless security policy.

"I didn't need a secret memo from Mr Gates to ascertain that. We do not have a coherent policy. I think that is pretty obvious," said Republican Senator John McCain, a tough critic of the man he lost to in the 2008 White House race.

"We keep threatening sanctions. For well over a year now, in fact, including the previous administration, we keep threatening. And obviously, we have not done anything that would in any way be viewed effective.

"We have to be willing to pull the trigger on significant sanctions and then we have to make plans for whatever contingencies follow if the sanctions are not effective," McCain, a Vietnam War hero considered a leading voice on defense matters in the US Congress, told the "Fox News Sunday" program.

The revelation about the memo followed closed-door meetings at the United Nations last week by envoys deliberating a fourth round of sanctions against Iran, which denies Western charges it is trying to build an atomic weapon.

Ambassadors from the five veto-wielding members of the UN Security Council -- Britain, China, France, Russia and the United States -- plus Germany huddled Wednesday and Thursday to try to find common ground on a draft resolution.

The meeting followed last week's historic nuclear conference in Washington that saw 47 nations attempt to reach agreement on tighter policing of loose materials that could be used to build an atomic weapon.

Iran announced plans on Sunday to hold talks "in the coming days" with all 15 members of the UN Security Council in an effort to break the deadlock over a long-stalled nuclear fuel deal.

Iranian Foreign Minister Manouchehr Mottaki said the deal could be finalized in "two weeks" if all sides showed the necessary will.

An October 2009 UN-drafted deal to supply nuclear fuel for a Tehran research reactor by shipping out Iran's low-enriched uranium in return for higher-grade nuclear fuel produced by Russia and France has been deadlocked for months.

The deal has floundered over Iran's insistence that it is only open to a simultaneous exchange inside the Islamic republic, a condition rejected by the world powers.

Iran on Sunday hosted a nuclear disarmament conference of its own, at which it rejected any attack on civilian atomic sites as a violation of international law and urged Israel to join the Non-Proliferation Treaty (NPT).