WASHINGTON — A former senior C.I.A. official says that officials in the Bush White House sought damaging personal information on a prominent American critic of the Iraq war in order to discredit him.

Juan Cole, a University of Michigan professor who writes an influential blog that criticized the war, was allegedly targeted by the CIA. Glenn L. Carle, a former Central Intelligence Agency officer who was a top counterterrorism official during the administration of President George W. Bush, said the White House at least twice asked intelligence officials to gather sensitive information on Juan Cole, a University of Michigan professor who writes an influential blog that criticized the war.

In an interview, Mr. Carle said his supervisor at the National Intelligence Council told him in 2005 that White House officials wanted “to get” Professor Cole, and made clear that he wanted Mr. Carle to collect information about him, an effort Mr. Carle rebuffed. Months later, Mr. Carle said, he confronted a C.I.A. official after learning of another attempt to collect information about Professor Cole. Mr. Carle said he contended at the time that such actions would have been unlawful.

It is not clear whether the White House received any damaging material about Professor Cole or whether the C.I.A. or other intelligence agencies ever provided any information or spied on him. Mr. Carle said that a memorandum written by his supervisor included derogatory details about Professor Cole, but that it may have been deleted before reaching the White House. Mr. Carle also said he did not know the origins of that information or who at the White House had requested it.

Intelligence officials disputed Mr. Carle’s account, saying that White House officials did ask about Professor Cole in 2006, but only to find out why he had been invited to C.I.A.-sponsored conferences on the Middle East. The officials said that the White House did not ask for sensitive personal information, and that the agency did not provide it.

“We’ve thoroughly researched our records, and any allegation that the C.I.A. provided private or derogatory information on Professor Cole to anyone is simply wrong,” said George Little, an agency spokesman.

Since a series of Watergate-era abuses involving spying on White House political enemies, the C.I.A. and other spy agencies have been prohibited from collecting intelligence concerning the activities of American citizens inside the United States.

“These allegations, if true, raise very troubling questions,” said Jeffrey H. Smith, a former C.I.A. general counsel. “The statute makes it very clear: you can’t spy on Americans.” Mr. Smith added that a 1981 executive order that prohibits the C.I.A. from spying on Americans places tight legal restrictions not only on the agency’s ability to collect information on United States citizens, but also on its retention or dissemination of that data.

Mr. Smith and several other experts on national security law said the question of whether government officials had crossed the line in the Cole matter would depend on the exact nature of any White House requests and whether any collection activities conducted by intelligence officials had been overly intrusive.

The experts said it might not be unlawful for the C.I.A. to provide the White House with open source material — from public databases or published material, for example — about an American citizen. But if the intent was to discredit a political critic, that would be improper, they said.

Mr. Carle, who retired in 2007, has not previously disclosed his allegations. He did so only after he was approached by The New York Times, which learned of the episode elsewhere. While Mr. Carle, 54, has written a book to be published next month about his role in the interrogation of a terrorism suspect, it does not include his allegations about the White House’s requests concerning the Michigan professor.

“I couldn’t believe this was happening,” Mr. Carle said. “People were accepting it, like you had to be part of the team.”

Professor Cole said he would have been a disappointing target for the White House. “They must have been dismayed at what a boring life I lead,” he said.

In 2005, after a long career in the C.I.A.’s clandestine service, Mr. Carle was working as a counterterrorism expert at the National Intelligence Council, a small organization that drafts assessments of critical issues drawn from reports by analysts throughout the intelligence community. The council was overseen by the newly created Office of the Director of National Intelligence.

Mr. Carle said that sometime that year, he was approached by his supervisor, David Low, about Professor Cole. Mr. Low and Mr. Carle have starkly different recollections of what happened. According to Mr. Carle, Mr. Low returned from a White House meeting one day and inquired who Juan Cole was, making clear that he wanted Mr. Carle to gather information on him. Mr. Carle recalled his boss saying, “The White House wants to get him.”

“ ‘What do you think we might know about him, or could find out that could discredit him?’ ” Mr. Low continued, according to Mr. Carle.

Mr. Carle said that he warned that it would be illegal to spy on Americans and refused to get involved, but that Mr. Low seemed to ignore him.

“But what might we know about him?” he said Mr. Low asked. “Does he drink? What are his views? Is he married?”

Mr. Carle said that he responded, “We don’t do those sorts of things,” but that Mr. Low appeared undeterred. “I was intensely disturbed by this,” Mr. Carle said.

He immediately went to see David Gordon, then the acting director of the council. Mr. Carle said that after he recounted his exchange with Mr. Low, Mr. Gordon responded that he would “never, never be involved in anything like that.”

 Mr. Low was not at work the next morning, Mr. Carle said. But on his way to a meeting in the C.I.A.’ s front office, a secretary asked if he would drop off a folder to be delivered by courier to the White House. Mr. Carle said he opened it and stopped cold. Inside, he recalled, was a memo from Mr. Low about Juan Cole that included a paragraph with “inappropriate, derogatory remarks” about his lifestyle. Mr. Carle said he could not recall those details nor the name of the White House addressee.

He took the document to Mr. Gordon right away, he said. The acting director scanned the memo, crossed out the personal data about Professor Cole with a red pen, and said he would handle it, Mr. Carle said. He added that he never talked to Mr. Low or Mr. Gordon about the memo again.

In an interview, Mr. Low took issue with Mr. Carle’s account, saying he would never have taken part in an effort to discredit a White House critic. “I have no recollection of that, and I certainly would not have been a party to something like that,” Mr. Low said. “That would have simply been out of bounds.”

Mr. Low, who no longer works in government, did recall being curious about Professor Cole. “I remember the name, as somebody I had never heard of, and who wrote on terrorism,” he said. “I don’t recall anything specific of how it came up or why.”

Mr. Gordon, who has also left government service, said that he did not dispute Mr. Carle’s account, but did not remember meeting with him to discuss efforts to discredit Professor Cole.

Several months after the initial incident, Mr. Carle said, a colleague on the National Intelligence Council asked him to look at an e-mail he had just received from a C.I.A. analyst. The analyst was seeking advice about an assignment from the executive assistant to the spy agency’s deputy director for intelligence, John A. Kringen, directing the analyst to collect information on Professor Cole.

Mr. Carle said his colleague, whom he declined to identify, was puzzled by the e-mail. Mr. Carle, though, said he tracked Mr. Kringen’s assistant down in the C.I.A. cafeteria.

“Have you read his stuff?” Mr. Carle recalled the assistant saying about Professor Cole. “He’s really hostile to the administration.”

 The assistant, whom Mr. Carle declined to identify, refused to say who was behind the order. Mr. Carle said he warned that he would go to the agency’s inspector general or general counsel if Mr. Kringen did not stop the inquiry.

Intelligence officials confirmed that the assistant sent e-mails to an analyst seeking information about Professor Cole in 2006. They said he had done so at the request of the Office of the Director of National Intelligence, which had been asked by White House officials to find out why Professor Cole had been invited to CIA-sponsored conferences.

John D. Negroponte, who was then the director of national intelligence, said that he did not recall the incident, but that the White House might have asked others in his office about Professor Cole. A spokeswoman for the office said there was no evidence that anyone there had gathered derogatory information about him.

Around the time that Mr. Carle says the White House requests were made, Professor Cole’s conservative critics were campaigning to block his possible appointment to Yale University’s faculty. In 2006, conservative columnists, bloggers and pundits with close ties to the Bush administration railed against him, accusing Professor Cole of being anti-American and anti-Israeli. Yale ultimately scuttled the appointment.

Professor Cole, 58, is still teaching at Michigan, and still writes his blog on the Middle East, called Informed Comment.