The Department of Justice has informed two Democratic senators that concerns they raised about departmental advice on harsh interrogation techniques are part of an internal investigation.

The department’s Office of Professional Responsibility is looking into “circumstances surrounding” the drafting of an August 2002 memo from the department’s Office of Legal Counsel to Alberto R. Gonzales, then President Bush’s White House counsel, regarding standards of conduct for interrogations, wrote H. Marshall Jarrett, the OPR counsel, in a Feb. 18 letter to Sens. Richard J. Durbin , D-Ill., and Sheldon Whitehouse , D-R.I.

Jarrett was responding to a Feb. 12 letter from the senators requesting a probe into the department’s role in authorizing and overseeing the use by the Central Intelligence Agency of waterboarding, an interrogation technique that simulates drowning.

Among the topics to be examined, Jarrett wrote, is “whether the legal advice contained in those memoranda was consistent with the professional standards that apply to Department of Justice attorneys.”

The letter appears to be a softening of the position taken previously by Attorney General Michael B. Mukasey , who said at a Jan. 30 Senate Judiciary hearing that he does not want to probe past conduct sanctioned by the Office of Legal Counsel because it would be inappropriate to take that step.

Appearing before the House Judiciary Committee on Feb. 6, Mukasey said the Justice Department would not probe the legality of waterboarding, even though a day earlier the CIA confirmed it had used waterboarding in interrogating three al Qaeda leaders several years earlier.

Responding to the Justice Department letter, Durbin said in a statement that the United States “has always repudiated waterboarding as a form of torture and prosecuted it as a war crime. Justice Department officials who ignored this history — even those at the highest levels — must be held accountable for their actions.”