The official, who asked not to be named, said Secretary of State Condoleezza Rice discussed the next steps with Iran with her EU, German, British and French counterparts over dinner Tuesday night in London.

"We had good discussions with the Europeans. We are looking at what we could do," the official told reporters on the plane taking Rice home after attending a conference on Palestinian reform in London.

"They said, 'Can you support a couple of things we want to do?' and we said we will try to get them an answer. We are looking at this. We will try to get an answer soon."

Deputy State Department spokesman Adam Ereli said discussions were continuing but added that there was no timetable for making a decision.

The United States, which had initially kept a distance from efforts by the "EU-3" to wean the Iranians off of their nuclear weapons aspirations, signaled Monday it was now studying ways of boosting its support.

Among the enticements reportedly under consideration were support for Iranian membership in the World Trade Organization (WTO) and an offer to help Tehran procure spare parts for its aging fleet of passenger airliners.

The senior official would not discuss the possible incentives that could be offered Iran but said the discussions with the Europeans were "moving along."

The United States was at the same time pursuing a harder line on Iran during a meeting in Vienna of the board of governors of the International Atomic Energy Agency (IAEA), the UN nuclear watchdog.

US delegation chief Jackie Sanders, citing "an alarming number" of unresolved questions about Iran's nuclear program, said the IAEA could not put off "forever" going before the UN Security Council for possible sanctions.

Rice referred to the dual approach in an interview Tuesday with the British television channel ITV.

"The United States has been clear that we are supportive of what the Europeans are trying to do in giving the Iranians an opportunity to show the world that they are prepared to live up to their obligations, and of course we retain the possibility of referral to the Security Council," she said.

The transatlantic allies have been working hard since President George W. Bush's trip to Europe last week to reconcile their approaches to the Iranian nuclear question that had produced some friction.

US officials had first seen the EU talks with Tehran as a fruitless exercise. The Europeans wanted more involvement from Washington and less sabre-rattling about the possible use of force against Iran.

The United States has also been sending out some apparently mixed signals on Iran's cooperation. Sanders' tough comments came a day after White House spokesman Scott McClellan said Tehran's level of cooperation was improving.

But Ereli denied there was any contradiction, saying that Iran had been responsive in some areas but "what they give with one hand they take away with another."

He said that overall, "there's a continuing pattern of evasion and obstruction and obfuscation that ... increases rather than diminishes our concerns."

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