The report published by the Post also said Zinke allowed his wife to travel with him in government vehicles in violation of department policy.
The report follows ethics investigations into several Trump administration officials, including Scott Pruitt, who stepped down as the head of the Environmental Protection Agency in July, and Tom Price, who resigned as health and human services secretary in September 2017.
Zinke said he did not ask his security detail to travel with him during the August 2017 vacation to Turkey and Greece, and the decision was made by the U.S. Park Police supervisor, the Interior Department’s Office of Inspector General said in the report.
The report said other officials in the department approved Zinke’s wife, Lolita, riding with him in government vehicles. It said that when Zinke was asked whether he knew the practice violated department policy, the secretary said it was consistent with government travel regulations.
The report listed several instances of official travel in which Zinke was accompanied by her wife and he reimbursed the government for her expenses.
It said Zinke had asked department employees to research whether his wife could be made an official Interior Department volunteer. He denied his intention in making the request was to enable his wife to travel with him in an official capacity.
“Ultimately, the employees advised him that making her a volunteer could be perceived negatively, and she did not become one,” the report said.
The Interior Department did not immediately respond to a Reuters request for comment.
The department’s Office of Inspector General has also said it was probing Zinke over the use of chartered flights and a Montana real estate deal.
Reporting by Mohammad Zargham; Editing by Peter Cooney