Attorney General Michael Mukasey refused Friday to give Congress details of the government's investigation into interrogations of terror suspects that were videotaped and destroyed by the CIA. He said doing so could raise questions about whether the inquiry is vulnerable to political pressures.

In letters to leaders of the House and Senate Judiciary committees that oversee the Justice Department, Mukasey said there is no need right now to appoint a special prosecutor to lead the investigation. The preliminary inquiry currently is being handled by the Justice Department and the CIA's inspector general.

"I am aware of no facts at present to suggest that department attorneys cannot conduct this inquiry in an impartial manner," Mukasey wrote Friday to Sens. Patrick Leahy of Vermont and Arlen Specter of Pennsylvania, the top Democrat and Republican, respectively, on the Senate Judiciary Committee. "If I become aware of information that leads me to a different conclusion, I will act on it."

Addressing congressional demands for facts in the CIA tapes inquiry, Mukasey noted that the Justice Department generally does not give out information about pending cases.

"This policy is based in part on our interest in avoiding any perception that our law enforcement decisions are subject to political influence," Mukasey wrote. "Accordingly, I will not at this time provide further information in response to your letter, but appreciate the committee's interests in this matter."

An almost-identical letter was sent Thursday to Democratic leaders of the House Judiciary Committee.

Responding, Leahy suggested that Mukasey's refusal amounts to a stonewalling of congressional oversight of the Justice Department.

"I am disappointed that the Department of Justice declined to provide us, either publicly or in a classified setting, with any of the information Senator Specter and I have requested," Leahy said in a statement.

"Oversight fosters accountability," Leahy said. "This committee needs to fully understand whether the government used cruel interrogation techniques and torture, contrary to our basic values."

Leahy said the tapes would be a top topic at his committee's hearing next week to consider the nomination of U.S. District Judge Mark Filip for deputy attorney general, the Justice Department's No. 2 official. It also will come up at oversight hearings of the Justice Department that Leahy said he would schedule for early next year.

The videotapes, made in 2002, showed the CIA's interrogations of two terror suspects. They were made to document how CIA officers used new, harsh questioning techniques approved by the White House to force recalcitrant prisoners to talk. The CIA destroyed the tapes in 2005.