The House Interior Committee will ask a U.S. District Court to invalidate the Interior Department's recent sale of coal leases in North Dakota, committee Democrats said yesterday after a caucus.

The confrontation over the lease sale, held in defiance of an Interior Committee resolution directing the department to postpone it, escalated yesterday after the agency disclosed that some of the leases from Wednesday's sale may be issued in 15 days.

This contrasted to a statement made by the department's lawyer to a federal judge last week that "We don't expect leases to be issued for something like 45 to 60 days, at the absolute earliest."

The accelerated schedule would allow the leases to take effect on Sept. 30, one day before a proposed moratorium on federal coal leasing would take effect if passed by the Senate. The measure passed the House last summer.

Interior Committee Democrats, who voted along party lines on Aug. 3 for a resolution directing Interior Secretary James G. Watt to postpone Wednesday's lease sale, viewed the 15-day notice from the department as "obviously another effort to circumvent the will of Congress," according to committee member John F. Seiberling (D-Ohio), who attended a Democratic caucus on the matter.

Watt said he defied the committee's directive because he considered it unconstitutional and unnecessary.

Deputy Assistant Interior Secretary J. Steven Griles said the department has not accelerated the leasing schedule in hopes of dodging a moratorium. He stressed the agency has given notice only that it "may" issue leases in 15 days, not that it "will."

The notice was given in a letter to the National Wildlife Federation, which has filed a lawsuit attempting to invalidate Wednesday's sale on the grounds that the Interior Committee's directive was constitutional. The committee's Democratic majority decided in caucuses over the last two days to enter the suit on the side of the federation, committee sources said.

Because there are 27 Democrats and 14 Republicans on the panel, this ensures a committee vote to challenge Watt, sources said. Watt argued the directive constituted a "legislative veto," which the Supreme Court struck down last summer.

U.S. District Court Judge Louis Oberdorfer postponed ruling on the case last Friday after an Interior Department lawyer told him the agency expected not to issue the leases for 45 to 60 days after Wednesday's sale.

"Watt's attempt to process the leases in the next 15 days is in direct conflict with what Watt's lawyers told a federal judge," said National Wildlife Federation official Norman Dean.

The group will "return to the courthouse as soon as possible to stop this illegal action," Dean said.

Interior's lawyer said at Friday's hearing that the agency would give the federation 15 days' notice before issuing leases from Wednesday's sale. Department officials said yesterday's letter complies with that agreement, although it occurred four weeks earlier than indicated.

Of the 540 million tons of coal offered for leasing on Wednesday, companies placed bids on only 140 million tons, contained in five tracts. There was only one bid per tract, four from the same company, and all bids were within $10 an acre of the government's $100 per-acre minimum bid.

Because of the slack bidding, Griles said the government will be able to process the leases more quickly than anticipated. The law requires the Interior Department to determine that the bids are at least equal to the fair market value of coal in the region, and requires the Justice Department to review them for possible antitrust violations.

"We understand that Justice is willing to process these without any delay," Griles said. The Interior Department would be required to perform lengthy market value tests only if there had been competition for the tracts, he added.