The agencies conducting the main federal investigation into the BP Deepwater Horizon explosion and spill said Friday that they had asked for and been given extra time to complete their report.

Associated Press

The Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement, which have been carrying out a joint investigation since shortly after the offshore well blew out in April, were to deliver their findings on Jan. 27. But the leaders of the inquiry, Commandant Admiral Robert J. Papp of the Coast Guard and Michael R. Bromwich, director of the ocean energy bureau, said they had been granted an additional 60 days to complete their work.

Officials involved in the inquiry said they needed the extra time to conduct forensic studies of the failed blowout preventer and other equipment related to the offshore rig and to hold another public hearing on the evidence. That hearing is tentatively scheduled for Jan. 24, with the final report now expected on March 27.

The two agencies have held several hearings featuring dramatic and at times contradictory testimony from survivors of the April 20 blowout, which killed 11 workers and unleashed the largest offshore oil spill in American history.

A parallel inquiry by a presidentially appointed investigative panel has said it will report its findings in January, although it is possible that deadline may slip as well.