Kash Patel, the F.B.I. director, has closed an internal watchdog office established in 2020 to uncover and reduce the risk of misuses of national security surveillance, according to officials familiar with the matter.

The elimination of the unit, the Office of Internal Auditing, comes as Congress debates whether to reauthorize a high-profile warrantless wiretapping law, Section 702 of the Foreign Intelligence Surveillance Act, or FISA. That law, which was a chief focus of the office, nearly collapsed last year before lawmakers extended it until April 2026.

The move is significant because it could give skeptics of the program new ammunition to argue that Congress should sharply curtail the law or even let it expire given that a guardrail has been discarded. It also poses a crucial test for Mr. Patel, who rose in pro-Trump circles by attacking the F.B.I. over its abuses of the surveillance law but said during his confirmation hearing that he saw the program as a vital tool for gathering foreign intelligence and protecting national security.

The F.B.I. did not comment. But the closure was part of a larger reorganization, according to people familiar with the matter, speaking on the condition of anonymity to discuss a sensitive matter. The functions of the office, along with another, the Office of Integrity and Compliance, which helps ensure that employees comply with laws, regulations and policies in general, have been absorbed by the Inspection Division.

The division is an internal affairs unit that examines agent shootings and allegations of misconduct.

Cindy Hall has abruptly retired as the leader of the internal auditing office. Efforts to reach her were unsuccessful, and the circumstances of her exit were not clear. A former official briefed on her departure was told that she had been forced out, while a person familiar with the matter said the bureau had characterized her departure to Congress as voluntary.