The White House is exploring allegations that the new President-elect of Iran, Mahmoud Ahmadinejad, was involved in the 1979 American Embassy siege in Tehran.

Scott McClellan, the White House press secretary said today that the Bush Administration was taking reports that American hostages remember Mr Ahmadinejad taking part in the hostage crisis "very seriously".

Mr Ahmadinejad's role in the crisis is disputed and rumours of his direct involvement are widely dismissed by insiders in Iran, including known hostage takers.

But Mr McClellan said today: "I think the news reports and statements from several former American hostages raise many questions about his past. We take them very seriously and we are looking into them to better understand the facts."

Five men held hostage during the siege identified Mr Ahmadinejad as one of their captors yesterday. Four of the former hostages e-mailed each other after watching television coverage of the Iranian elections to share their surprise at recognising Mr Ahmadinejad 25 years after the siege, which lasted 444 days and has darkened relations between America and Iran ever since.

"This is the guy. There’s no question about it," said Chuck Scott, a 73-year old retired Army colonel and one of 52 Americans that were taken hostage for more than a year after the Iranian Revolution.

"You could make him a blond and shave his whiskers, put him in a zoot suit and I’d still spot him."

Mr Scott and former hostages David Roeder, William J. Daugherty and Don A. Sharer all told the Associated Press yesterday that they had no doubt that Mr Ahmadinejad, elected last week as the new President of Iran, was one of the hostage takers.

Both Mr Scott and Mr Roeder, who worked for the CIA in Iran, said that Mr Ahmadinejad, who takes office on August 4, had a senior role among militants who took over the embassy and was present when they were interrogated.

"I can absolutely guarantee you he was not only one of the hostage takers, he was present at my personal interrogation," said Mr Roeder. "It was almost like he was checking on the interrogation techniques they were using in a sort of adviser capacity."

A fifth hostage, Kevin Hermening confirmed his memory of Mr Ahmadinejad after looking at recent photographs. Other hostages have said that they cannot specifically recall Mr Ahmadinejad taking part in the siege.

"My memories were more of the gun barrel, not the people behind it," said Paul Lewis, a former Marine who was guarding the embassy when it was captured on November 4 1979.

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