A House committee investigating the Enron affair is refusing on constitutional grounds to turn over to Arthur Andersen's attorneys documents related to the panel's interviews of Andersen's chief auditor on the Enron account.

The refusal by the House Energy and Commerce Committee to honor a subpoena from Andersen comes as the accounting firm is scheduled to face trial Monday on a criminal obstruction charge for destruction of Enron-related documents. Andersen attorneys delivered the subpoena last Thursday to the Office of General Counsel of the House.

"We're going to fight it," Ken Johnson, a spokesman for committee chairman Rep. Billy Tauzin, R-La., said Tuesday. "This information clearly is protected by the Constitution's speech and debate clause."

The Andersen auditor, David Duncan, has pleaded guilty to ordering the shredding of Enron documents and had agreed to cooperate with federal prosecutors.

The subpoena requests all documents related to the committee investigators' dealings with Duncan, including notes and reports of interview with him, correspondence and related documents, Johnson said. At a public committee hearing in January, Duncan invoked his Fifth Amendment right against self-incrimination and refused to answer questions.

Johnson said there was no "smoking gun" in the interview material from Duncan and that "The idea that we're holding something back is ridiculous." The committee is withholding the material on constitutional grounds, he said.

He said the panel had gathered the material "for the sole purpose of preserving it, not destroying it."

Andersen attorneys didn't immediately return telephone calls seeking comment.

Duncan's lawyer, Robert Giuffra, declined comment.

On Friday, a federal judge in Houston refused to delay the May 6 trial of Andersen.

Attorney Rusty Hardin, who had insisted on a speedy trial after Andersen was indicted in March, told U.S. District Judge Melinda Harmon his client has been hurt by media coverage and prospective jurors have formed negative opinions about the firm.

Talks between Andersen and the Justice Department collapsed on April 18. The government had offered to defer any criminal prosecution of Andersen for up to three years, requiring the Big Five accounting firm to cooperate in the investigation of its former client Enron and to promise not to violate any laws during that period.

Chicago-based Andersen, struggling to survive as it loses clients, partners and employees, in January acknowledged massive shredding of documents and deletion of computer files related to Enron's audits last fall after the Securities and Exchange Commission began an investigation into the now-bankrupt energy-trading company.