A new dispute in California over whether and how ship hulls must be cleaned before disposal has prompted the maritime agency to suspend issuing any new contracts for its entire national fleet of obsolete vessels.

Officials said Tuesday they could not estimate how long the suspension will last.

If the problem is resolved within months, the impact on the James River ghost fleet may be small. All the ships considered at greatest environmental risk have been removed from the James, agency officials have said, and the focus next year would be on the California and Texas fleets.

But the program's suspension comes as another embarrassment to an agency that failed to meet a congressional mandate to eliminate a backlog of aging, obsolete ships by last September.

Maritime Administrator Sean Connaughton, who took office last fall, acknowledged disappointment in the need for a suspension, but said it was his only recourse.

"Our main focus is to dispose of these vessels in the safest and most environmentally responsible manner possible," Connaughton said. "If there are legitimate questions, we must go back and examine it."

While some delays in the removal of environmentally hazardous ships are now required, he said, "It's better to deal with it upfront than have the whole program be implicated in the long term."

The latest environmental problems began last year, when the U.S. Coast Guard told the maritime agency it must begin complying with regulations on ship cleaning that had been in place since 2004.

The move appeared to catch the maritime agency by surprise, partly because Navy and Coast Guard vessels are exempt from the regulations. Coast Guard officials acknowledged it took time to interpret the regulations and their impact on the Maritime Administration, or MARAD, an arm of the U.S. Transportation Department.

"There was some lack of clarity as to whether this regulation applied to MARAD or not," said Angela McArdle, a Coast Guard spokeswoman. "We determined that it did."

The regulation, aimed at protecting U.S. waters from the unintentional introduction of non-native species, requires ship owners to remove all "fouling organisms"-- such as grass, moss and mussels -- from the hull, piping and tanks "on a regular basis."

MARAD began complying last year by cleaning hulls with a brush in a process known as scamping, said Shannon Russell, an agency spokeswoman.

But California officials protested the cleaning, saying MARAD may need to acquire a permit before such work can begin in California waters. Connaughton said his agency is working with state officials in all affected states to determine whether a permit is needed.

While MARAD has said the cleaning process poses no environmental risk, others say it requires further study after one report in California claimed sheets of decayed metal had come off a ship being cleaned.

There is currently a backlog of about 44 deteriorating ships in the James that could pose an environmental risk as they age. Some of the ships are contaminated with asbestos and cancer-causing PCBs.