NEW ORLEANS — An internal review of the Coast Guard’s performance during the BP oil spill cleanup last year has concluded that the agency was caught badly unprepared and that the response operation was dogged from the beginning by significant planning failures.

The report, which was commissioned by the Coast Guard, found that the agency’s preparedness for environmental crises had “atrophied over the past decade” as the guard confronted its expanded security responsibilities in the post-9/11 world. This resulted in significant coordination and communication problems during the spill response as well as a lack of familiarity with long-established procedures among many of the response workers.

The review, completed in January, was quietly made public by the Coast Guard last month. It was prepared by a team of experts that included two retired Coast Guard admirals as well as officials from several federal and state agencies, with substantial involvement from representatives from the oil industry, the spill response industry and the environmental community.

The Coast Guard has prepared these reports, called incident specific preparedness reviews, to identify areas for improvement after major operations. The report found that both the government and private sector “demonstrated a serious deficiency in planning and preparedness for an uncontrolled release of oil from an offshore drilling operation.”