WASHINGTON - Congressional intelligence committees had at least a hint in October 2001 that the National Security Agency was expanding its surveillance activities after the 9/11 attacks, according to a letter released Tuesday by House Minority Leader Nancy Pelosi

The California Democrat had raised questions to Gen. Michael Hayden, then the NSA director, about the legal authority to conduct the eavesdropping work.

In the October 2001 letter, Pelosi said she was told in a briefing that month that the agency "had been operating since the Sept. 11 attacks with an expansive view" of its authorities "to the conduct of electronic surveillance under the Foreign Intelligence Surveillance Act and related statutes, orders, regulations and guidelines."

"I am concerned whether, and to what extent, the National Security Agency has received specific presidential authorization for the operations you are conducting," Pelosi, then the top Democrat on the intelligence panel, wrote Hayden.

President Bush has acknowledged he authorized the NSA to eavesdrop — without warrants — on international calls and e-mails of Americans and others inside the United States with suspected ties to al-Qaida or its affiliates.

"I can say that if somebody from al-Qaida is calling you, we'd like to know why," Bush said this week. "This program is conscious of people's civil liberties, as am I."

Bush and other senior officials have said he personally renewed the program more than three dozen times since October 2001, and a small group of Congress members was briefed on the highly classified effort.

But it appears that Hayden may have at least alluded broadly to the new surveillance work with a wider audience of House and Senate intelligence committee members during the classified October briefing. According to Pelosi's letter, Hayden spoke about the agency's new posture to expand its operations.

Hayden, who is now the nation's No. 2 intelligence official, told Pelosi he wanted to clarify ambiguities. "In my briefing, I was attempting to emphasize that I used my authorities to adjust NSA's collection and reporting," he wrote on Oct. 18, 2001.

The subsequent crucial sentences of the letter, released Tuesday, were blocked out for security reasons.

Key parts of Pelosi's letter were also withheld. For instance, one sentence indicates that the NSA was forwarding intercepts and other undisclosed information to the FBI without first getting a request.

A series of independent commissions have encouraged national security agencies to improve cooperation. But it is far from clear in the letter how this work may be happening.

Said Steven Aftergood, a government secrecy expert with the Federation of American Scientists: "It does seem that the NSA is doing something different and in a different way than what it has done before."