The American Civil Liberties Union pointed to the documents as evidence that the Bush administration has reacted to the Sept. 11, 2001, terrorist attacks on the United States by blurring the distinction between terrorism and political protest. FBI officials defended the involvement of counterterrorism agents in providing security for the Republican and Democratic conventions as an administrative convenience.

The documents were released by the FBI in response to a lawsuit filed by a coalition of civil rights, animal rights and environmental groups that say they have been subjected to scrutiny by task forces set up to combat terrorism. The FBI has denied targeting the groups because of their political views.

"It's increasingly clear that the government is involved in political surveillance of organizations that are involved in nothing more than lawful First Amendment activities," said Anthony Romero, executive director of the ACLU. "It raises very serious questions about whether the FBI is back to its old tricks."

A Sept. 4, 2003, document addressed to the FBI counterterrorism unit described plans by a group calling itself RNC Not Welcome to "disrupt" the 2004 Republican National Convention in New York. It also described Internet postings from an umbrella organization known as United for Peace and Justice, which was coordinating worldwide protests against the convention.

"It's one thing to monitor protests and protest organizers, but quite another thing to refer them to your counterterrorism unit," said Leslie Cagan, national coordinator for United for Peace and Justice.

Another document, addressed to the Joint Terrorism Task Force, which coordinates anti-terrorist activities by the FBI and local police forces, described threats to disrupt the Democratic National Convention in Boston.

Responding to the lawsuit filed in May in U.S. District Court in Washington, the FBI said it had identified 1,173 pages of records relating to the ACLU and 2,383 pages relating to Greenpeace. The content of the records, which were generated since 2001, is not known.

FBI spokesmen declined to discuss the case on the record on the grounds that it is being adjudicated. Speaking on background, an FBI official said that many of the records were routine correspondence. He said the FBI counterterrorism unit received reports on possible threats to the 2004 political conventions because of its role in ensuring security.