SAN FRANCISCO -- A Hong Kong-based company that operated the container ship that struck a bridge support in the San Francisco Bay last year has been indicted for allegedly doctoring paperwork in an attempt to thwart investigators looking into the incident.

A federal grand jury charged Fleet Management Ltd. on Tuesday with six felony counts of making false statements and obstructing justice. Prosecutors announced the indictment Wednesday morning.

According to a Department of Justice summary of the indictment, unidentified "senior ship officers and shore-based supervisory officials concealed and covered up documents with an intent to impede, obstruct and influence the investigation of the spill."

Among the allegedly falsified documents were the ship's passage plan for its scheduled Nov. 7 journey from the Port of Oakland to South Korea, and two prior trips made after the company took over the operation of the ship a few days before the incident.

Under U.S. law, passage plans are required for each voyage. Fleet Management "falsified and forged these plans after the crash and concealed and covered up the real ship records," prosecutors said.

The indictment also charges Fleet Management with two counts of misdemeanor crimes under the Clean Water Act and the Migratory Bird Treaty Act for negligently causing the crash, which dumped 53,000 gallons of toxic bunker fuel into the bay. The spill killed and injured thousands of birds and fouled beaches throughout Northern California.

The negligence allegedly stemmed from Fleet Management's failure to adequately train a new crew it had installed after taking over operation of the Cosco Busan and for failing to post an adequate lookout.

Under the latest environmental-crimes indictment, Fleet Management is charged as a co-defendant alongside Capt. John Cota, the ship pilot whose job was to guide the giant container vessel from the port out to sea.

Cota has been charged with two felony counts of lying to Coast Guard officials about his prescription drug use and two misdemeanor environmental crimes.

Fleet Management could face fines of $500,000, or twice the losses caused by the alleged violations, for each obstruction and false-statements count. The penalties for the Clean Water Act violations could range as high as $200,000, or twice the losses. The migratory bird count could bring fines as large as $10,000 or twice the losses.

Fleet Management is already being sued by the Justice Department for breaking environmental laws. The lawsuit filed last year accused Fleet Management and others of "fault, negligence and breach of federal safety and operating regulations."

In a prepared statement, Fleet Management said Wednesday the company itself had discovered that "discrepancies exist between the facts as understood and reported prior to its investigation." It did not elaborate.

But it said it had advised the Justice Department of its finding. The company said it had "suspended the individuals involved in the misunderstanding of the facts pending completion of the company's internal investigation."

But it said it "does not believe that these new facts have any bearing on the accident or on the pilot's navigation of the ship."

Fleet Management said it "will evaluate the government's allegations and address them as appropriate in court." It said it would continue to cooperate with ongoing investigations.

Regal Stone Ltd., the ship's owners, who hired Fleet Management, said it "noted with disappointment" the new indictment.

The new charges of falsifying documents come as prosecutors were investigating the possibility that the Chinese crew of the ship altered certain unidentified records after the Cosco Busan accident. It was not immediately clear whether the indictments and that thread of the probe are connected.

Josh Eaton, a spokesman for U.S. Attorney Joseph P. Russoniello, said he declined to comment beyond what was in the indictment.

Jeff Bornstein, an attorney for Cota, said he reviewed evidence from prosecutors that showed crew members had admitted in the last two months they had not been adequately trained and had falsified "key navigational records." The doctoring of certain documents, including passage plans, had been done "at the direction of a very high-level Fleet official in the hours or days after the accident," Bornstein said.

The new charges bolster Cota's contention that "this was a series of errors that involved other people and other factors," Bornstein said in a telephone interview.

Cota had boarded the Cosco Busan assuming, as all pilots must, that the crew knew how to operate key equipment, his lawyer said.

The new charges complicated the case of whether six Chinese crew members who have been held in Northern California as "material witnesses" for eight months in the case against Cota should be held at least until October to testify at Cota's scheduled trial. Last week, Cota's lawyers said there was reason to believe certain crew members had not told the truth and requested that they be held until Cota's trial.

The crew members appeared at a hearing Wednesday to address that issue. But Mark Greenberg, a lawyer representing Fleet Management, said he had just reviewed the new indictment and would need two more weeks to process the charges and the evidence. The judge set another hearing for Aug. 7.