Interior secretary has not been keeping proper travel records: Watchdog A number of administration officials have come under scrutiny for travel issues.

 -- The office of Secretary of the Interior Ryan Zinke was warned Wednesday that an investigation into Zinke's official travel was delayed by "absent, or incomplete documentation," the latest snag in the months-long controversy over Trump administration officials' travel.

The Interior Department's inspector general issued the management advisory to Zinke's office, explaining that paperwork for the secretary's travel was insufficient and that the department's ethics office had not included sufficient documentation in its trip reviewing process. Such warnings are given when the department needs to be made aware of a deficiency immediately, so it may begin working to correct it, according to a spokesperson.

The advisory further notes that the inspector general has been unable to determine the number of trips by which Zinke was accompanied by his wife, Lolita Zinke, due to the incomplete records. It does state that, aside from the documentation issue, the department has cooperated with the probe.

Scrutiny of Cabinet members' travel reached its apex earlier in the fall after a number of officials found themselves in the midst of inquiries over their use of private and military aircraft in lieu of commercial flights. Secretary of Health and Human Services Tom Price resigned in late September, expressing regret that the issue of his more than 25 chartered and military flights "created a distraction."

The investigation into Ryan Zinke's travel began after he chartered three flights since March totaling $12,375. A spokesperson for the secretary has said that commercial options weren't viable in each instance. Other officials whose travel is under audit include Secretary of the Treasury Steve Mnuchin and EPA Administrator Scott Pruitt.

The Interior Department's inspector general's office is asking Ryan Zinke's office to provide complete documentation by Dec. 11 as well as develop better procedures to process travel documents in the future.

Deputy Interior Secretary David Bernhardt blamed his and Ryan Zinke's predecessors at the department in his response to the inspector general's letter, writing: "When I arrived at the department … it was clear to me that the secretary and I inherited an organizational and operational mess from the previous administration."

Bernhardt added that they are following the same procedures used under former Secretary Sally Jewell and that they "remain dysfunctional." He pledged that the department will work to provide documents for travel in 2017 and will start documenting travel for Lolita Zinke.