What officials here describe as a government-wide inquiry was launched after several of the former hostages from the embassy takeover came forward to say that the Iranian president-elect had been one of their captors.
A group of Iranian militants, with at least tacit approval of the newly-established revolutionary government in Tehran, stormed the U.S. embassy in November 1979 and took some 90 people inside as prisoners.
More than 50 U.S. diplomats and other officials were held hostage for 444 days in an affair that produced a rupture in official U.S.-Iranian political relations that lasts to this day.
Aides to the Iranian president-elect, a former mayor of Tehran, have denied he was involved in storming the embassy but reportedly have been less clear about whether he had any part in the long-running hostage incident.
At the White House, National Security Adviser Steven Hadley told reporters no determination has been made about Mr. Ahmadinejad's role, but said testimony of the former hostages raises questions that are being looked into.
At a news briefing, State Department Spokesman Sean McCormack said memories of the hostage-taking have not faded and that the charges are being taken seriously.
"We have not forgotten. We have not forgotten that fact that 51 of our diplomats were held for 444 days," he said. "They were taken hostage. The secretary of state takes very seriously her responsibility to protect, as best she can, the men and women of the State Department and those who serve in our embassies abroad. The Iranian government, with respect to this question, has an obligation to speak definitively concerning these questions that have been raised in public by these stories."
Mr. McCormack said U.S. officials will speak to the former hostages, at least one of whom is still an active-duty foreign service officer. But he indicated there would be no direct overture to Iran over the issue.
Though the two governments do not have diplomatic relations, they have had occasional political contacts in recent years on matters of mutual concern including developments in Iraq and Afghanistan.
Officials here would not address what the implications would be if the Iranian president-elect was confirmed to have been among the hostage-takers.
Spokesman McCormack said it is not a matter just for the United States, and that at stake are questions about the ability of diplomats around the world, under international treaties and conventions, to freely do their work while posted abroad.