WASHINGTON (AP) _ The Treasury Department kept backup copies of deleted computer files that could contain evidence in a lawsuit over American Indian trust funds, government lawyers said Thursday.

The federal lawyers notified a court-appointed investigator Tuesday that Treasury workers had deleted computerized check records more than seven years old in June 1998. The Treasury Department has been under a court order since 1996 to preserve all records related to the trust accounts for individual Indians at the core of the multibillion dollar lawsuit.

Treasury Department officials did more checking and found the backup copies of the data deleted in 1998, Justice Department lawyer Brian Ferrell wrote to the investigator, Alan Balaran.

``The initial fear that data from the system was lost was unfounded,'' Ferrell wrote.

The records at issue would help lawyers for the Indians find checks written to trust fund account holders during parts of 1990 and 1991.

A group of Indians is suing over mismanagement of about 300,000 trust accounts now worth about $500 million. The accounts hold the proceeds of government-approved leases on Indian lands for activities such as grazing, logging, mining or oil drilling.