NEW ORLEANS (AP) -- Transocean Deepwater Drilling Corp. has lost a round in its fight to avoid handing over documents to a government board investigating the 2010 Deepwater Horizon oil rig explosion.

Transocean is appealing a federal court order enforcing a subpoena of the documents by the U.S. Chemical Safety and Hazard Investigation Board.

The 5th Circuit Court of Appeals on Tuesday refused to stay the document handover while the appeal is pending.

"We are extremely pleased with the court's decision," said Dr. Daniel Horowitz, CSB's managing director. "After years of litigation, it paves the way for the CSB to finally conclude its Deepwater investigation, which we believe holds lessons for all the energy industry."

The documents were collected by a Transocean internal investigation team.

The 5th Circuit said Transocean failed to justify action that would delay the safety board's report on the explosion, which killed 11 and spawned the nation's worst offshore oil spill.

"Transocean has resisted the subpoenas for thirty-one months, of which twenty-one were consumed by litigation. An appeal in this court could take anywhere from one to three years," the opinion by a three-judge panel of the 5th Circuit said. "By the time the subpoenas' enforceability is finally determined, a delay in the documents' release may cause the CSB to have missed the opportunity to prevent another accident of the type that occurred on the Deepwater Horizon, which itself resulted in eleven deaths."

Transocean owned the Deepwater Horizon drilling rig, which exploded and sank over BP's Macondo well.

Transocean lawyers were not immediately available for comment.