Department spokesman Sean McCormack said Mohammad Nahavandian was in town but added, "He's not here for meetings with US government officials to my knowledge; certainly not with members of the State Department."

McCormack said Nahavandian had not been issued a visa but was in the United States legally. He did not elaborate but said only, "There are a variety of other ways for an individual to arrive in the country."

The Washington foray by Nahavandian, described as an economic aide to Iran's top nuclear negotiator Ali Larijani, was first reported 10 days ago by Britain's Financial Times newspaper.

The rare sighting of a senior Iranian official in Washington comes at a moment when Iran's showdown with the West over its suspected nuclear weapons activities was nearing a climax.

Iran has announced plans to speed its research into uranium enrichment while the United States and its allies are pushing for UN sanctions against the Islamic republic.

The Financial Times quoted an Iranian adviser as saying Nahavandian had come here to discuss the possibility of wide-ranging direct talks between the two countries, which have not had diplomatic relations for a quarter-century.

The United States has authorized its ambassador in Baghdad, Zalmay Khalilzad, to hold direct discussions with the Iranians about Iraq but nothing else.

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