WASHINGTON  Federal inspectors charged with ensuring the safety of offshore oil drilling are overwhelmed, insufficiently trained, work without official procedures for some of their most crucial decisions and sometimes have insufficient support from their supervisors for resisting industry influence, according to a report released Tuesday by the Interior Department’s inspector general.

The report, which examined the practices of the Bureau of Ocean Energy Management, Regulation and Enforcement, echoes the findings of an earlier investigation by the department released in September, and is based on much of the same raw material. But the new report offers additional recommendations and provides new details of the problems in the agency, which until last spring was called the Minerals Management Service.

The Obama administration reorganized the agency after the April 20 explosion on the Deepwater Horizon rig that killed 11 workers and resulted in the worst offshore oil spill in the nation’s history.

Mary L. Kendall, the inspector general, acknowledged that some of the report’s findings might be outdated. But Michael R. Bromwich, the head of the offshore drilling safety agency, said in a letter to Interior Secretary Ken Salazar that the new report was filled with “serious deficiencies and errors.” The report, Mr. Bromwich said, failed to take account of recent reforms in the agency, which he said was “curious, especially given that this information is readily available.”