A federal appeals court decided Tuesday that it was unreasonable to require a historical accounting of money the government has been managing for Indian tribes, saying the bookkeeping chore would "take 200 years."

The U.S. Court of Appeals for the District of Columbia sided with the government and the tribes in their effort to block a lower court order for a detailed tally of money owed the tribes going back to 1887.

The accounting had been ordered by U.S. District Judge Royce Lamberth, who is overseeing a class-action lawsuit in which thousands of Indians claim they were cheated out of more than $100 billion in oil, gas, grazing, timber and other royalties overseen by the Interior Department.

In their appeals, the government and the Indians argued that the massive historical accounting Lamberth ordered would cost up to $13 billion — far more than was reasonable.

On Tuesday, a three judge appeals panel agreed, overturning the accounting and calling Lamberth's decision "ill-founded," an abuse of discretion and was not favored by either side in the lawsuit.

Appellate Judge Stephen F. Williams wrote that the accounting ordered by Lamberth "would not be finished for about 200 years, generations beyond the lifetimes of all now living beneficiaries."

The issue of how to determine what is owed the Indians has gone back and forth from Lamberth to the appeals court repeatedly during the almost 10 years since Blackfeet Indian Elouise Cobell filed the lawsuit.

An 1887 law allotted land to individual Indians and provided that the government would hold the land and any revenue from it in trust for the Indians and their survivors. For 20 years before Cobell sued, several reports criticized the government's management. In 1994, Congress ordered that the money be accounted for.

The appeals court said the accounting ordered by Lamberth, who wanted a much more detailed look at records, improperly expanded the scope of what Congress authorized. The judge should have allowed the Interior Department more latitude in deciding how to perform the accounting, the appeals court wrote.

Interior Secretary Gale Norton said in a statement that she was pleased by the decision.

"Thus far, the department has expended more than $100 million in its historical accounting effort and has found ample evidence that monies collected for individual Indians were distributed to the correct recipients," she said.

Lawyers for the Indians said they were not surprised by the ruling but did not want to comment until they had examined the decision, said Bill McAllister, a spokesman.

Lamberth has excoriated the government's treatment of the Indians in past decisions. This fall, he ordered the Interior Department to disconnect all computer systems with access to Indian accounts. He said the department's security was so bad, hackers could easily manipulate the data. The appeals court granted the department a temporary reprieve so it could appeal.

Earlier this year, the Indians offered to settle the case for $27.5 billion. House and Senate lawmakers say the amount is too high, but they have been working on legislation that would resolve the case.