Washington • Republicans on the House Natural Resources Committee are asking the Interior Department to provide documents on use of private charter flights for government business by the past three Interior secretaries, including two who served under President Barack Obama.

Reps. Rob Bishop of Utah and Bruce Westerman of Arkansas said they are seeking the information following news reports that Trump administration officials, including Interior Secretary Ryan Zinke, used non-commercial flights costing taxpayers tens of thousands of dollars. Bishop chairs the Natural Resources panel, while Westerman leads an oversight and investigations subcommittee.

The lawmakers said Wednesday that “federal officials should be held to the highest ethical standard” in adhering to rules regarding transparency and responsible use of taxpayer dollars. That includes Zinke and former Interior secretaries Sally Jewell and Ken Salazar, the GOP lawmakers said.

“When violations occur, the public deserves to know. When willful violations occur, there should be consequences,” the Bishop and Westerman said.

At the same time, “when partisan opportunists conflate diligent conformance to scandal, no one wins,” they added. “Let’s get all facts on the table, ensure taxpayers are protected and proceed with the peoples’ business.”

Zinke said last week he’s taken three charter flights while in office, including a $12,375 late-night trip from Las Vegas to his home state of Montana in June. Zinke said no commercial flight was available when he planned to fly for a speech to Western governors.

Zinke also traveled by private plane in Alaska in May and to the U.S. Virgin Islands in March. The two trips cost a total of $7,000, the Interior Department said.

Zinke has no plans to reimburse the government, spokeswoman Heather Swift said Tuesday. All of Zinke’s flights — including a military flight with Agriculture Secretary Sonny Perdue to view wildfires in Montana in August — were approved by career officials at the department, she said.

“As with previous (Interior) secretaries, Secretary Zinke’s travel is paid for by the government,” Swift said.

The independent Office of Special Counsel is investigating a complaint that Zinke’s speech to a Las Vegas hockey team may have violated the Hatch Act, which prohibits executive branch officials from engaging in political activities. The team’s owner contributed to Zinke’s congressional campaigns and to Trump’s inauguration.