WASHINGTON, Oct. 17  Leaders of the Senate Intelligence Committee reached a tentative agreement on Wednesday with the Bush administration that would give telephone carriers legal immunity for any role they played in the National Security Agency’s domestic eavesdropping program approved by President Bush after the Sept. 11 terrorist attacks, a Congressional official said Wednesday.

Senators this week began reviewing classified documents related to the participation of the telephone carriers in the security agency program and came away from that early review convinced that the companies had “acted in good faith” in cooperating with what they believed was a legal and presidentially authorized program and that they should not be punished through civil litigation for their roles, the official said.

As part of legislation on the security agency’s wiretapping authorities, the White House has been pushing hard for weeks to get immunity for the telecommunications companies in discussions with Senator John D. Rockefeller IV of West Virginia, the Democratic chairman of the Senate Intelligence Committee, and Senator Christopher S. Bond of Missouri, the ranking Republican. A tentative deal was first reported by The Washington Post.

The Intelligence Committee will begin reviewing the legislation at a closed session on Thursday.

The agreement between the Senate Intelligence Committee and the Bush administration would also include a greater role for the secret intelligence court in overseeing and approving methods of wiretapping used by the security agency, the official said.