NEW ORLEANS - Flaws in Transocean Ltd.'s emergency training and equipment and a poor safety culture contributed to the deadly Deepwater Horizon drilling rig explosion that led to the Gulf oil spill, according to a Coast Guard report released Friday.

The report centered on Transocean's role in the disaster because it owned the rig and was primarily responsible for ensuring its safety, the Coast Guard said. BP PLC owned the well that blew out.

The Coast Guard report also concluded that decisions made by workers aboard the rig "may have affected the explosions or their impact," such as failing to follow procedures for notifying other crew members about the emergency after the blast.

The report doesn't explore the root causes of the well blowout, which triggered the explosions that killed 11 workers and sent millions of gallons of oil spewing into the Gulf of Mexico. But the Coast Guard said numerous actions by Transocean and the rig's crew affected their ability to prevent or limit the disaster.

Electrical equipment that may have ignited the explosion was poorly maintained, while gas alarms and automatic shutdown systems were bypassed so that they did not alert the crew, the report said. And rig workers didn't receive adequate training on how and when to disconnect the rig from the well to avoid an explosion, it said.

"These deficiencies indicate that Transocean's failure to have an effective safety management system and instill a culture that emphasizes and ensures safety contributed to this disaster," the report said.

Transocean spokesman Brian Kennedy said the Coast Guard inspected the Deepwater Horizon seven months before the blowout and certified it as being fully compliant with all applicable marine safety compliance standards.

"We strongly disagree with - and documentary evidence in the Coast Guard's possession refutes - key findings in this report," Kennedy said in a statement.

The report also found lax oversight by the rig's flag state, the Republic of the Marshall Islands, a Pacific nation where Transocean registered the Deepwater Horizon in 2005. It said the Coast Guard should ramp up its inspections of such foreign-flagged drilling rigs.

The Marshall Islands does not inspect rigs itself and instead farms out the work to qualified third parties. In the case of the Deepwater Horizon, inspections were done by the American Bureau of Shipping and Det Norske Veritas. The Marshall Islands "effectively abdicated its vessel inspection responsibilities," the report said.

Bill Gallagher, the senior deputy commissioner of maritime affairs for the Marshall Islands, blasted the Coast Guard report. He noted that the Coast Guard also has third parties perform inspections.

"We are followng pretty much the same route the Coast Guard takes," he said. "It's a bit of the pot calling the kettle black."

The Bureau of Ocean Energy Management Regulation and Enforcement is expected to release its own report on the explosion before issuing a joint final report with the Coast Guard later this year.

Previously, a presidential commission pointed to a cascade of technical and managerial failures, including a faulty cement job and a poor safety culture in the industry. BP's own internal investigation spread the blame for the disaster among all the partners on the rig. A panel looking into why a key safety device, the blowout preventer, failed to do its job pointed to a faulty design, among other problems. The Chemical Safety Board, the Justice Department and other entities have yet to release their own findings.

The courts will also be assigning blame and liability, and officials of the oil companies could even be held criminally negligent.

The Coast Guard's report said electrical equipment on board, some of which was severely corroded, may not have been able to prevent flammable gases from igniting.

Gas detectors on board the rig were not set to automatically activate an emergency shutdown system to stop the engines and halt the flow of outside air into engine rooms, and the bridge crew had not been trained on when they should activate the systems. If the shutdown system had been activated as soon as gas was detected, the explosions in the engine room area could have been delayed or avoided, the report said.

The Deepwater Horizon had an onboard system for fighting fires, but it wouldn't work without electrical power. When the power went out on board, crews realized it would be futile to try to fight the fire, the report said.

The report also faulted the culture on board for problems fighting the fire, noting that drills were held at the same time on the same day each week, and that drill personnel were sometimes allowed to skip the exercises.

Records indicate that "the routine, repetitive nature of the fire drills may have led to a degree of complacency among the crew members," the report said.

Despite recommendations that the blowout preventer - the device that failed to prevent the oil spill - be inspected every three to five years, Transocean did not arrange to have the Deepwater Horizon's blowout preventer recertified for more than 10 years, the report said.

"Transocean failed to ensure that its onboard management team and crew had sufficient training and knowledge to take full responsibility for the safety of the vessel," the report said.

Associated Press writer Cain Burdeau contributed to this report.