"We expect and hope that we would be able to offer a revised (fuel swap) proposal to Iran should there be talks in the near future, but we are still working on the specific details," State Department spokesman P.J. Crowley said.

The New York Times cited a senior US official as saying Washington and its allies were close to an agreement on a proposed deal, an assessment echoed by a Western diplomat in Washington.

Crowley cautioned that even if the fuel exchange plan for the Tehran Research Reactor, or TRR, is revived, possibly in talks the Western powers hope to hold with Iran in Vienna next month, it would still not resolve wider concerns about Iran's nuclear intentions.

"There is a recognition that an updated TRR proposal can be helpful as a confidence building measure," Crowley said.

"You should not confuse the advancement of a TRR proposal with the core concerns that we continue to have on Iran's nuclear program and its character.

The New York Times reported intelligence analysts had concluded last year's fuel exchange proposal was scuttled by Iran's supreme leader, Ayatollah Ali Khamenei, and that many officials therefore suspected that this latest effort would also fail.

Iran, which has ruled out halting sensitive nuclear work that can have both civilian and military uses, has welcomed the offer of talks with the major powers but has yet to formally reply to the invitation for a meeting from November 15 to 17.