WASHINGTON - The U.S. Army inspector general is investigating whether aides to former Afghanistan commander Gen. Stanley McChrystal were insubordinate when they made a series of derogatory comments about top civilian leaders to a Rolling Stone reporter, McClatchy Newspapers has learned.

The investigation comes as the Pentagon grapples with how much access the reporter who wrote the piece, Michael Hastings, should have to troops. Hastings was banned from a scheduled embed this September in Afghanistan for being untrustworthy, Col. David Lapan, the director of the Pentagon press office, said Tuesday.

Last month, however, the Army granted Hastings an interview with forces he had embedded with previously in Afghanistan, saying it saw no harm.

The IG investigators have finished questioning officials and are completing the investigation, Army officials said. The officials confirmed the investigation but would not say who asked for it or specify what its scope is. The investigation began shortly after McChrystal was relieved of his command in June.

Maj. Gen. William McCoy Jr. said the investigation "is in review."

Among those who have been interviewed are staff members of Rolling Stone, one Defense Department official told McClatchy. He spoke only on the condition of anonymity because the investigation is continuing.

Hastings said he declined to be interviewed or participate in the Army investigation.