WASHINGTON — The Osage Nation and the Department of Justice signed a $380 million settlement Friday, ending a 12-year-old lawsuit concerning accounting and management of the tribe’s trust funds and assets.

Under the terms of the settlement, the federal government will pay the Osage Nation $380 million for its claims of historical losses to its trust funds and interest income as a result of the government’s mismanagement of trust assets. To date, it is the largest settlement of a claim made by a tribe against the United States.

A trial over outstanding claims was scheduled to begin in February 2012. The settlement is currently before the U.S. Treasury for confirmation of payment from the Judgment Fund, with payments to individuals expected to start by Dec. 5.

“I am pleased that this settlement has finally come about,” Osage Chief John Red Eagle said. “Too many tribal elders have passed on waiting for this day. This is a great day for the Osage Tribe.”

“This historic settlement resolves with finality long-standing trust accounting and trust management claims by the Osage Tribe,” said US Assistant Attorney General Ignacia Moreno. “This settlement demonstrates the United States’ strong commitment to resolving pending tribal trust accounting and trust management cases in an expedited, fair and just manner.”

As part of the agreement, the Department of the Interior will regularly provide the Osage Nation with statements of account, audits and information regarding the tribe’s assets.

Both sides agreed on dispute resolution provisions in the settlement to minimize the possibility of future lawsuits.

The Osage Nation, based in Pawhuska, Okla., had filed suit against the federal government in 1999 and 2000 over the Department of the Interior’s accounting and management practices. The tribe had also sued in 2004 in the U.S. District Court for the District of Columbia in a trust accounting case but dropped the suit in 2010.

Between 2004 and 2010, the tribe received two judgments worth $331 million from the U.S. Court of Federal Claims for previous claims dating back to 1972.