Aerial view of Oklahoma City after the bombing — CBS News Washington bureau chief denies he was being cultivated as an informant around the time of the 1995 Oklahoma City bombing. (Win McNamee/Reuters)

The Center for Public Integrity said in a statement Tuesday that “a once-classified FBI memo reveals that the bureau treated a senior ABC News journalist as a potential confidential informant in the 1990s.” The Center went on to say the unnamed ABC News journalist revealed the name of a source to the FBI in a follow-up interview, about a year after contacting the FBI with information about the perpetrator of the Oklahoma City bombing and additional bombings being planned in two other cities – information that turned out to be erroneous.

Later in the day, Gawker named Isham as the subject of the story, citing unnamed sources.

“The suggestion that I was an informant for the FBI is outrageous and untrue,” Isham said in a statement, issued to the press Tuesday afternoon, in response to the Gawker story.

“Like every investigative reporter, my job for 25 years has been to check out information and tips from sources. In the heat of the Oklahoma City bombing, it would not be unusual for me or any journalist to run information by a source within the FBI for confirmation or to notify authorities about a pending terrorist attack. This is consistent with the policies at every news organization. But at no time did I compromise a confidential source with the FBI or anyone else.”

In its report, the center had said that the unnamed ABC News journalist had revealed to the FBI that the source of the information he’d gotten about the bombing had been a former CIA officer named Vincent Cannistraro who was on contract to the network as a consultant.

“Mr. Cannistraro was not a confidential source, but rather a colleague - a paid consultant to ABC News who had already spoken to the FBI about information he had received,” Isham said in his statement.

CBS News also issued a statement Tuesday:

“CBS News has strict standards regarding the handling of source material and we are discussing the facts of the allegations with Chris,” adding, “The events in question are a matter between the FBI and ABC News.”