WASHINGTON -- The Coast Guard has found serious safety and environmental violations on a Shell drilling rig used in the Arctic waters off Alaska, another blow to the company's controversial bid to harvest oil in the petroleum-rich but sensitive region.

The Coast Guard said Friday that it has turned over the matter to the U.S. Department of Justice, which had no comment.

The Coast Guard found 16 violations on the Noble Discoverer, one of Shell's two drilling rigs for Alaska's Arctic waters. The company's other rig, the Kulluk, has its own troubles. The Kulluk broke free from towlines during a New Year's Eve storm and was grounded for several days off Kodiak Island.

Details of the Noble Discoverer's violations were obtained by Democratic staff of the House Natural Resources Committee, which had asked the Coast Guard for an accounting of inspections that took place on the rig at the end of November.

"The reports that Shell may have been drilling this summer using a drill ship with serious deficiencies in its safety and pollution control equipment raise additional and continued questions about whether Shell is able to drill safely offshore in the Arctic," Massachusetts Rep. Ed Markey, the top Democrat on the committee, wrote Friday to Shell's president.

The Coast Guard found the Noble Discoverer could not go fast enough to safely maneuver on its own in all the expected conditions found in Alaska's Arctic waters.

The Coast Guard also found "systematic failure and lack of main engine preventative maintenance," which caused a propulsion loss and exhaust system explosion.

Among other issues listed were inoperable equipment used to measure the oil in water that is dumped overboard, improper line splices throughout the engine room, piston cooling water contaminated with sludge and an abnormal propeller shaft vibration.

Coast Guard spokesman Kip Wadlow said he couldn't discuss the details because the investigation has been forwarded to the Justice Department. Wadlow declined to say whether the Coast Guard believed criminal penalties could be warranted.

Wadlow said the investigation started after the Noble Discoverer had problems with its propulsion system while pulling into the port of Seward, Alaska, in late November.

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