WASHINGTON — House Democrats demanded yesterday that the Justice Department turn over two secret memos that reportedly authorize painful interrogation tactics against terror suspects — despite the Bush administration’s insistence that it has not violated American anti-torture laws.

Spokesmen for the White House and the Justice Department said a memo written in February 2005 on this subject did not change an administration policy issued in 2004 that publicly renounced torture as “abhorrent.”

The House Judiciary chairman, Rep. John Conyers, and Rep. Jerrold Nadler, a Democrat of New York, promised a congressional inquiry into the two Justice Department legal opinions that reportedly “explicitly authorized the use of painful and psychological tactics on terrorism suspects.”

“Both the alleged content of these opinions and the fact that they have been kept secret from Congress are extremely troubling, especially in light of the department’s 2004 withdrawal of an earlier opinion similarly approving such methods,” Mr. Conyers, a Democrat of Michigan, with Mr. Nadler, a fellow House Judiciary member, wrote in a letter yesterday to Acting Attorney General Peter Keisler. The two Democrats also asked that Steven Bradbury, Justice’s acting chief of legal counsel, “be made available for prompt committee hearings.”

The memos were disclosed in yesterday’s editions of the New York Times, which reported that the 2005 legal opinion authorized the use of simulated drownings and freezing temperatures while interrogating terror suspects, and was issued shortly after then-Attorney General Alberto Gonzales took over the Justice Department. That secret opinion, which explicitly allowed using the painful methods in combination, came months after a 2004 opinion in which the Justice Department publicly declared torture “abhorrent” and the administration seemed to back away from claiming authority for such practices.

A White House spokeswoman, Dana Perino, denied that the 2005 opinion cleared the way for the return of painful interrogation tactics or superseded American anti-torture law. “This country does not torture,” she told reporters. “It is a policy of the United States that we do not torture, and we do not.” Ms. Perino did confirm existence of the February 5, 2005, classified opinion, however. But she would not comment on whether it authorized specific practices, such as head-slapping and simulated drowning, and said the 2005 opinion did not reinterpret the law.

Additionally, a Justice Department spokesman, Brian Roehrkasse, said the 2004 opinion remains in effect and that “neither Attorney General Gonzales nor anyone else within the department modified or withdrew that opinion.”

“Accordingly, any advice that the department would have provided in this area would rely upon, and be fully consistent with, the legal standards articulated in the December 2004 memorandum,” Mr. Roehrkasse said in a statement.

The dispute may come down to how the White House defines torture, or whether it allowed American interrogators to interpret anti-torture laws beyond legal limits. A CIA spokesman, George Little, said the agency sought guidance from the Bush administration and Congress to make sure its program to detain and interrogate terror suspects followed American law.