WASHINGTON, Jan. 4 (Xinhuanet) -- The U.S. National Security Agency (NSA) acted on its own authority, without a formal directive from President George W. Bush, to expand its domestic surveillance operations in the weeks after the Sept. 11, 2001, attacks, declassified documents showed.

   The documents released on Tuesday showed that the NSA operation prompted questions from a leading Democrat, Representative Nancy Pelosi of California, who said in an Oct. 11, 2001, letter to a top intelligence official that she was concerned about the agency's legal authority to expand its domestic operations, The New York Times reported Wednesday.

   "I am concerned whether and to what extent the National Security Agency has received specific presidential authorization for the operations you are conducting," Pelosi wrote.

   Pelosi's letter showed much earlier concerns among lawmakers about the agency's domestic surveillance operations than had been previously known. Similar objections were expressed by Senator John D. Rockefeller IV, Democrat of West Virginia, in a secret letter to Vice President Dick Cheney nearly two years later.

   The letter also suggested that the security agency, whose mission is to eavesdrop on foreign communications, moved immediately after the Sept. 11 attacks to identify terror suspects at home by loosening restrictions on domestic eavesdropping, the report said.

   Pelosi wrote to Lt. Gen. Michael V. Hayden, then head of the NSA, to express her concerns after she and other members of the House and Senate Intelligence Committees received a classified briefing from Hayden on Oct. 1, 2001, about the agency's operations.

   Bush administration officials said on Tuesday that Hayden, now the country's No. 2 intelligence official, had acted on the authority previously granted to the NSA, relying on an intelligence directive issued by former President Ronald Reagan in 1981.

   In 2002, Bush signed an executive order specifically authorizing the security agency to eavesdrop without warrants on the international communications of Americans inside the United States who the agency believed were connected to Al-Qaida. The disclosure of the domestic spying program last month provoked an outcry in Washington, where Congressional hearings are planned. Enditem