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.

Barclay Walsh contributed research.