Already saddled with resolving a looming nuclear showdown with Iran, the Bush administration now faces the possibility that that country's new leader helped take 52 Americans hostage in 1979.

"Many questions" have been raised by six former U.S. hostages who have identified Iran's President-elect Mahmoud Ahmadinejad (search) as one of their captors more than 25 years ago, President Bush said Thursday

"I have no information," Bush said in an interview with foreign reporters ahead of a trip to Scotland next week. "But obviously his involvement raises many questions

Earlier, the White House indicated that some kind of investigation was in the works.

"I think the news reports and statements from several former American hostages raise many questions about his past," White House press secretary Scott McClellan said. "We take them very seriously and we are looking into them to better understand the facts."

Five Americans who were held for more than a year in the hostage crisis believe that Ahmadinejad was one of their captors.

"You don't forget, even years later," Chuck Scott told FOX News on Thursday. "Even if he dyed his hair blond and shaved his beard, I'd still recognize him."

Scott and fellow former hostages David Roeder (search), William J. Daugherty (search), Don A. Sharer (search), Kevin Hermening (search) and William A. Gallegos (search) agreed that Ahmadinejad, 49, was one of the hostage-takers, The Associated Press first reported Wednesday.

Scott, who described Ahmadinejad as being a "terrorist," said the new Iranian president sat in on parts of his monthlong interrogation and whispered guidance to the men who were questioning him.

"It shouldn't surprise anyone that someone with hostage-taking in his resume should rise to high political office in Iran," the retired Army colonel said.

Not everyone agrees. Former hostage and retired Air Force Col. Thomas E. Schaefer (search), of Peoria, Ariz., said he doesn't recognize Ahmadinejad, by face or name, as one of his captors.

Several former students among the hostage-takers also said Ahmadinejad did not participate. And a close aide to Ahmadinejad denied the president-elect took part in the seizure of the embassy or in holding Americans hostage.

Militant students seized the U.S. Embassy in Tehran on Nov. 4, 1979, and held 52 Americans hostage for 444 days to protest Washington's refusal to hand over the U.S.-backed Shah Mohammad Reza Pahlavi (search) for trial. The shah fled Iran earlier that year after he was overthrown by the Islamic Revolution.

Ahmadinejad was a member of the Office of Strengthening Unity, the student organization that planned the embassy takeover, but he was opposed to taking the U.S. Embassy, several of his associates said.

The aide, Meisan Rowhani, told the AP from Tehran that Ahmadinejad was asked during recent private meetings if he had a role in the hostage taking.

Rowhani said he replied, "No. I believed that if we do that the world will swallow us."

Mohammad Ali Sayed Nejad, a longtime friend of the president-elect, said that in 1979, "Ahmadinejad had focused his fight against communism and Marxism and he was one of the opponents of seizing the U.S. Embassy. He was a constant opponent."

But the allegations about the hard-liner, if proven true, may not come as a complete surprise.

"He accused the Iranian negotiators of being weaklings," said former Ambassador Dennis Ross, FOX News foreign affairs analyst and fellow at the Washington Institute for Near East Policy.

Ahmadinejad, the hard-line mayor of Tehran, was declared winner Wednesday of Iran's presidential runoff election, defeating one of Iran's best-known statesmen, Ayatollah Hashemi Rafsanjani (search). The stunning upset put conservatives firmly in control of all branches of power in the Islamic Republic of Iran.

Ross said it was difficult to predict how the charges against Ahmadinejad would affect the negotiations on Iran's nuclear program.

"The critical issue is what is the policy going to be," Ross told FOX News. "There were people who were part of the takeover who have changed completely [but] his behavior doesn't appear to be different. He appears to be the same kind of firebrand he was before."

Though Ahmadinejad is Iran's leader in name, most experts believe that the true power is held by that country's mullahs.

"Whoever's president isn't the one who holds the keys to the palace," Ross said.

Still, Ahmadinejad ran on a populist platform, and appears to have been embraced by the majority of Iranians. Ross said he is known as the "Islamic Robin Hood."

That some former hostages were not sure Ahmadinejad was one of their captors was sure to complicate any investigation.

Former Marine embassy guard Paul Lewis (search) of Sidney, Ill., said he thought Ahmadinejad looked vaguely familiar when he saw a picture of him on the news last week, but "my memories were more of the gun barrel, not the people behind it."

Ex-hostage Alan Golacinski (search) also said he couldn't be certain.

"I can't identify this individual as one of my interrogators because I was blindfolded during all of my interrogations," said Golacinski, who was an embassy security officer. However, Golacinski said, "He did look somewhat familiar."

Scott and Roeder both said they were sure Ahmadinejad was present while they were interrogated.

"I can absolutely guarantee you he was not only one of the hostage-takers, he was present at my personal interrogation," Roeder said in an interview from his home in Pinehurst, N.C.

Daugherty, who worked for the CIA in Iran and now lives in Savannah, said a man he's convinced was Ahmadinejad was among a group of ringleaders escorting a Vatican representative during a visit in the early days of the hostage crisis.

"It's impossible to forget a guy like that," Daugherty said. "Clearly the way he acted, the fact he gave orders, that he was older, most certainly he was one of the ringleaders."

In a first-person account on the British Broadcasting Corp. Web site, world affairs editor John Simpson said he, too, recognized Ahmadinejad, saying there was something "faintly familiar" about him.

"I realized where I must have seen him: in the former American embassy in Tehran," Simpson wrote.

Scott, Roeder, Daugherty and Sharer said they have been exchanging e-mails since seeing Ahmadinejad emerge as a serious contender in Iran's elections.

"He was extremely cruel," said Sharer, of Bedford, Ind. "He's one of the hard-liners. So that tells you where their government's going to stand for the next four to five years."

After seeing recent newspaper photos, Sharer said, "I don't have any doubts" that Ahmadinejad was a hostage-taker.

A memory expert cautioned that people who discuss their recollections can influence one another in reinforcing false memories. Also, it's harder to identify from memory someone of a different race or ethnicity, said psychologist Elizabeth Loftus of the University of California, Irvine.

"Twenty-five years is an awfully long time," Loftus said. "Of course we can't say this is false, but these things can lead people down the path of having a false memory."

Scott gave a detailed account of the man he recalled as Ahmadinejad, saying he appeared to be a security chief among the hostage-takers.

"He kind of stayed in the background most of the time," Scott said. "But he was in on some of the interrogations. And he was in on my interrogation at the time they were working me over."

Scott also recalled an incident while he was held in the Evin prison in north Tehran in the summer of 1980.

One of the guards, whom Scott called Akbar, would sometimes let Scott and Sharer out to walk the narrow, 20-foot hallway outside their cells, he said. One day, Scott said, the man he believes was Ahmadinejad saw them walking and chastised the guard.

"He was the security chief, supposedly," Scott said. "When he found out Akbar had let us out of our cells at all, he chewed out Akbar. I speak Farsi. He said, `These guys are dogs, they're pigs, they're animals. They don't deserve to be let out of their cells.'"

Scott recalled responding to the man's stare by openly cursing his captor in Farsi. "He looked a little flustered, like he didn't know what to do. He just walked out."

Roeder said he's sure Ahmadinejad was present during one of his interrogations when the hostage-takers threatened to kidnap his son in the United States and "start sending pieces — toes and fingers of my son — to my wife."

Hermening, of Mosinee, Wis., the youngest of the hostages, said that after he looked at photos and did research on the Internet, he came to the conclusion that Ahmadinejad was one of his questioners.

Hermening had been Marine guard at the embassy, and he recalled the man he believes was Ahmadinejad asking him for the combination to a safe.

"His English would have been fairly strong. I couldn't say that about all the guards," Hermening said. "I remember that he was certainly direct, threatening, very unfriendly."

Rowhani, the aide to Ahmadinejad, said Ahmadinejad said during the recent meeting that he stopped opposing the embassy seizure after the revolution's leader, Ayatollah Ruhollah Khomeini (search), expressed support for it. But the president-elect said he never took part.

"Definitely he was not among the students who took part in the seizure," said Abbas Abdi, the leader of the hostage-takers. Abdi has since become a leading supporter of reform and sharply opposed Ahmadinejad. "He was not part of us. He played no role in the seizure, let alone being responsible for security" for the students.

Another of the hostage-takers, Bijan Adibi, said Ahmadinejad "was not involved. There was no one by that name among the students who took part in the U.S. Embassy seizure."

The Associated Press contributed to this report.