Smoking appears to have sparked a fire that caused $70 million in damage to the nuclear-powered aircraft carrier USS George Washington, Navy officials said Wednesday.

The announcement by the Navy came as Adm. Robert F. Willard, commander of the U.S. Pacific Fleet, relieved the carrier's commanding officer, Capt. David C. Dykhoff, and the executive officer of duty, Capt. David M. Dober.

Willard cited lost confidence in the commanding officer and his failure to meet mission standards after the investigation found unauthorized smoking by a crew member appeared to have ignited flammable liquids and other combustible material that were improperly stored. The other officer was relieved of duty for substandard performance.

"The fire and the subsequent magnitude of the fire were the result of a series of human acts that could have been prevented," according to a statement released by the Naval Air Forces in San Diego.

The Norfolk, Virginia-based carrier was en route from Chile to San Diego when the fire began on May 22.

"The smoking was happening in an unauthorized space and the evidence points to it probably was a lit cigarette that ignited the oil," said Capt. Scott Gureck, a spokesman for the U.S. Pacific Fleet. He said the investigation did not reveal who was smoking.

Flames were initially spotted near the auxiliary boiler room and air conditioning and refrigeration space in the rear of the ship. The safety of the ship's nuclear reactor was not threatened.

Navy officials now say it took about 12 hours to put out the fire because of the location and size. Fire and heat damaged electrical cabling and components running through 80 of the 3,800 compartments across several decks of the carrier.

The crew of the carrier has been temporarily assigned to shore duty in San Diego since shortly after the fire.

Capt. J.R. Haley, who previously commanded the nuclear-powered carrier USS Theodore Roosevelt, has taken command of the carrier, replacing Dykhoff. Capt. Karl O. Thomas has replaced Dober. Dykhoff and Dober have been temporarily assigned to shore duty with the Pacific Fleet, Walker said.

The Navy also revised the number of sailors injured during the fire from 23 to 37, saying 36 sailors were treated for minor injuries suffered while fighting the fire and one sailor suffered minor burns. All were returned to duty shortly afterward.

Gureck would not comment on whether the Navy was considering further disciplinary action against the two officers or possibly other people.

He said Rear Adm. Richard B. Wren, currently the USS Kitty Hawk carrier strike group commander, will decide what additional administrative and disciplinary measures, if any, will be taken when he becomes the USS George Washington strike group commander.

The carrier was initially expected to arrive in Japan in early August to replace the USS Kitty Hawk, which is being decommissioned. The George Washington, which is now scheduled to depart San Diego in late August, is due to be stationed at the U.S. naval base in Yokosuka.

The USS George Washington, the fourth Navy ship to bear the name, was commissioned July 4, 1992. It is a Nimitz class nuclear-powered supercarrier with a crew of 3,000 but can carry up to 5,000.