Washington ? The Interior Department ordered oil and gas companies, after an audit found they underpaid for production in 2001, to pay $2 million more in royalties to American Indian tribes and landowners.

About $210 million in gas royalties were collected in 2001, meaning the underpayment was less than 1 percent, according to the Interior Department’s Minerals Management Service.

Patrick Etchart, a spokesman for the agency, said Wednesday underpayments could happen when companies prepay royalties based on estimates that turn out to be low.

Companies were told of the discrepancies, and they can contest the finding, Etchart said. For now, MMS is not releasing the names of the companies ordered to pay the additional royalties.

In 2000, MMS also found companies underpaid for production and should pay $1.6 million more in royalties on American Indian lands.

MMS collects mineral revenues from about 3,800 leases on American Indian lands, then transfers that money to the Bureau of Indian Affairs to be paid to the Indian landowners.