WASHINGTON — An Interior Department official on Wednesday urged Congress to intervene in a dispute over billions of dollars that the federal government was supposed to hold in trust for Indians.

‘‘This is an issue that the department will not solve on its own,'' Interior Department associate deputy secretary James Cason told the House Resources Committee. ‘‘It will require the cooperation of many people, including Congress.''

The request came one day after a 44-day trial about the issue concluded. The lead defendant in the lawsuit, Elouise Cobell, a banker and Blackfoot Indian from Montana, criticized a Congressional effort to settle the dispute.

Congress passed legislation in 1994 that required the department to account for all the money in the fund and fix the accounting and payment process. Since then little progress has been made.

In 1996, Cobell filed a lawsuit demanding a full accounting of the fund.

In 1999, Judge Royce C. Lamberth ordered the department to provide a full accounting of how much the Indians are owed.

Cobell and Lamberth have criticized the department for not being able to devise a method for determining how much Indians are owed.

At the last day of the trial, Cobell's attorney asked Lamberth to order the Department of the Interior to reimburse the plaintiffs through a plan they devised that accounts for funds collected from oil, gas, timber and grazing royalties and other uses of Indian land.

Despite the conclusion of the trial, the issue is likely to fester in the courts for years through several rounds of appeals.

Neither the Interior Department nor Cobell ceded ground on Wednesday.

The department has proposed a five-year, $335 million plan to provide the full accounting of how much the department owes American Indians.