Interior Secretary Ryan Zinke and several staffers chartered an oil company plane for a flight from Las Vegas to Zinke’s home state of Montana in June, costing taxpayers $12,375, according to reports.

Zinke’s expensive travel puts him on a growing list of Trump administration officials who have been using taxpayer dollars to fly on non-commercial planes.

He and several staffers flew on a Beechcraft King Air 200 from Las Vegas, where Zinke had a speaking engagement, to Montana on June 26, an internal calendar obtained by Politico revealed. The plane, according to The Washington Post, belongs to Nielson & Associates, a Wyoming-based oil-and-gas exploration firm. The Interior Department paid for the charter.

After attending meetings and posing for magazine photo shoots, Zinke and his staff flew back to Washington on a commercial flight, according to the reports.

Zinke and his staff also flew chartered planes in March between the islands of St. Croix and St. Thomas for a trip that included a snorkeling tour, according to the reports. The former congressman has flown on military aircraft several times as interior secretary, including trips to Norway and Alaska in May, New Mexico in June, and to Montana in August.

The Interior Department said in a statement to HuffPost Friday that Zinke’s travel “was completely compliant with all applicable laws, rules, and regulations.”

Interior spokeswoman Heather Swift justified the non-commercial flying by claiming there were no commercial flights that fit Zinke’s schedule. The expense was paid out of the department’s budget and was “pre-cleared by career officials in the ethics office,” Politico said.

Swift couldn’t say how much Zinke’s private airplane travel in the Virgin Islands cost the government, according to the Post. There are at least four St. Croix-St. Thomas flights per day, according to Google Flights, and a round trip costs a few hundred dollars.

Environmental Protection Agency Administrator Scott Pruitt, Treasury Secretary Steven Mnuchin, and Health and Human Services Secretary Tom Price are all under fire for lavish travel that stuck taxpayers with the bill.

Price on Thursday pledged to reimburse the government for his seat on private charters, which have cost upwards of $400,000.

President Donald Trump said Wednesday he is “not happy” about Price’s travel and left open the option of firing him, telling reporters “we’ll see” when pressed on the matter.

Mnuchin, who raised eyebrows when his wife Louise Linton posted a photo on Instagram of the couple exiting a government private plane, said Thursday that he plans to continue using military planes when there’s a national security reason.

UPDATE: 8:42 a.m. ― A joint statement was released by Melinda Loftin (Department of the Interior designated agency ethics official and director of the Departmental Ethics Office) and Edward Keable (deputy solicitor, Division of General Law), both career members of the Interior Department’s Senior Executive Service:

The Scheduling Office meets regularly with the Departmental Ethics Office and the Division of General Law to ensure that all travel is thoroughly reviewed and approved in advance and that it is fully compliant with all applicable laws, rules, and regulations. Consistent with this process, the trip was reviewed and approved in advance by both the Departmental Ethics Office and the Division of General Law. In short, the trip ― including the Secretary’s address to the hockey developmental squad ― was completely compliant with all applicable laws, rules, and regulations.