The US and its allies are reviewing a proposal that would commit the UN Security Council to hold off on new sanctions on Iran if Teheran stops further development of its uranium enrichment program, diplomats said Friday. In continuing efforts to restart nuclear talks with Iran, the public stance by Washington and its key backers remains a full enrichment freeze; Iran not only would have to stop expanding its capacities, but would also need to stop reprocessing nuclear material and building equipment used for that process. But the review reflects potential readiness to compromise on that demand by accepting Iran's relatively advanced enrichment program - at least initially - in exchange for renewed multilateral negotiations that aim at a long-term freeze and a rollback of the activity. Diplomats told The Associated Press earlier this month that - while the United States remained opposed - the idea was being informally discussed among Britain, France and Germany as a possible way of ending the deadlock over enrichment and permitting a resumption of talks on the issue. On Friday they said that the idea had become more concrete, with Britain recently drafting a proposal that now was being circulated among the six nations seeking to engage Iran at the negotiating table - the United States and the four other Security Council members and Germany. Existence of a British draft was first reported by Newsweek on Friday. "The 'freeze for freeze' is an apparent precondition for the negotiations," said one of the diplomats, alluding to Security Council readiness to "freeze" work on new sanctions if Teheran agrees to keep the status-quo on enrichment and agrees to resume negotiations. "But the ultimate goal remains long-term suspension." There have been other encouraging indications of movement on the nuclear impasse. Iran recently pledged to answer key outstanding questions on nearly two decades of nuclear activities - most of it clandestine until revealed by a dissident group four years ago. Besides demanding an enrichment freeze - and a stop to construction of a plutonium-producing reactor - the Security Council has called on Iran to provide answers to the International Atomic Energy Agency on activities that could be linked to a weapons program and has slapped two sets of sanctions on Teheran because of its defiance. While the key issue remains enrichment, any follow-through by Iran on its decision to share sensitive information with the IAEA could feed sentiment for a compromise that would allow it to retain some elements of its enrichment program. Officials told AP last month that Iran had considered stopping some - but not all - of its enriched-uranium producing centrifuges last year in exchange for negotiations. But the US, Britain and France continued to insist on a full freeze. The issue gained in importance last month when IAEA chief Mohamed ElBaradei sent a report to the Security Council that says Iran has expanded its enrichment activities instead of freezing them - a finding that could act as a trigger for a third set of sanctions. The compromise being discussed derives from a Swiss proposal under which Iran would not expand its enrichment work in exchange for the Security Council not imposing further sanctions while diplomats pursue a resumption of formal negotiations. Multilateral talks with Iran broke off in August 2005 after Teheran rejected an offer of political and economic incentives in exchange for a pledge for long-term suspension and resumed its enrichment activities. Since then, Iran has repeatedly said an enrichment freeze was out of the question while the six world powers insisted they would accept nothing less as a condition for resuming negotiations. Iran's ultimate stated goal is running 54,000 centrifuges to churn out enriched uranium. It now has more than 3,000 operating and producing small low-enriched quantities that can be used to generate power - which Iran says is its only goal. But concerns that Teheran might decide to process uranium to weapons-grade material that is suitable for the fissile core of nuclear warheads led last year to Security Council involvement.