"It might be time to consider a different approach toward the new, more radical, more intolerant Iranian regime," Nicholas Burns, number three in the State Department, said in a speech here.

"Through its diplomatic contacts and its trade and investment, the world does have leverage -- and that leverage should be used constructively now -- to convince the hard-liners in Tehran that there is a price for their misguided policies," Burns said.

The United States has long sought UN action to head off Iran's suspected bid to develop a nuclear bomb. Lacking sufficient support, Washington has backed a European attempt to rein Tehran in with economic and security incentives.

But as the talks floundered, Burns said there was "a widening circle of countries ... that are willing to use their diplomatic and economic leverage to convince the Iranians" to scrap their nuclear aspirations.

Speaking to reporters after his speech, Burns said Russia, the European Union, China, Japan, India and Australia were all concerned by Iran's activities, and pressure on Tehran next year would be a "positive development."

Asked if he was proposing the EU impose sanctions if diplomatic talks with Iran fail, the undersecretary of state for political affairs said, "That is up to the EU to decide. It is not up to the US."

But he added, "All of us around the world have to think about how we can influence that government. And it is certainly one way that many countries around the world can do that."

The United States acknowledges having little leverage itself with the Iranians, having cut off diplomatic ties and progressively imposed economic sanctions since the 1979 seizure of US hostages in Tehran.

Burns spoke amid efforts to revive on-again, off-again negotiations between Iran and the so-called EU-3 grouping Britain, France and Germany and lately backed by Russia.

Diplomats said Wednesday they had hoped the talks would resume next week but the meeting might be put off until mid-December or early January because of squabbling over matters of substance and form.

The negotiations have been bogged down over Tehran's resumption of previously suspended uranium-conversion operations for a program the Iranians insists is strictly peaceful in nature.

But Burns did not give up hope for a diplomatic solution to the dispute, telling an audience at Johns Hopkins University here, "It is not too late for Iran to reconsider its nuclear ambitions."

"The United States is working closely with the Europeans, Russia, India, China and other countries with the hope of forming one increasingly united and purposeful coalition to deter Iran's efforts," he said.

"This circle of countries is widening. Iran should listen to the call for it to return to active and sustained negotiations with Europe."

Burns said if Iran resisted it would face referral by the International Atomic Energy Agency to the UN Security Council for possible sanctions.

But he added, "We remain confident that a united, international consensus can, in a peaceful way, convince Iran to turn back from its nuclear ambitions."

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