Employees at the U.S. Department of the Interior routinely violate federal policy by approving their own travel and charging thousands of dollars in unsupported costs to the government, according to auditors.

The department's review system is so lax that supervisors sign questionable expense reports without requiring any proof for inappropriate costs, said the auditors for the Interior Inspector-General.

"With more than 40 percent of statements in our sample reflecting some sort of discrepancy, this issue is both a significant internal control weakness and breakdown," the IG said.

A review by The Washington Examiner found similar problems at the departments of energy and agriculture, as well as NASA.

The Interior IG audits of the Bureau of Land Management and Office of Surface Mining and Reclamation's travel card programs found a laundry list of problems with travel approval and reimbursement.

DOI employees book travel through the GovTrip expense-tracking program. Many of BLM's 11,000 employees and OSM's 500 employees are authorized to use GovTrip's "auto approve" feature, allowing them to circumvent supervisor approval for airline tickets, rental cars, upgrades and hotels.

Of the 90 OSM travel vouchers reviewed by the IG, 89 were auto-approved through GovTrip. Although only 18 of the 99 BLM travel vouchers the IG reviewed were auto-approved, the report said many BLM employees are authorized to use the feature.

"The internal control safeguard inherent in obtaining supervisory approval for the use of staff time and travel funds before the trip begins is being circumvented, thus increasing the potential for fraud, waste, or mismanagement to go undetected," the IG said.

Auto-approval, a carryover from the pre-digital days of the government's paper-based system, was intended to streamline emergency travel, but DOI's lax review process allows fraud and abuse of the GovTrip system, the IG said.

Charge card statements -- the only travel document supervisors are required to review -- were approved even when they lacked signatures or receipts, or charged for thousands of dollars in unauthorized travel expenses.

In a review of 46 charge card statements, questionable charges by BLM travelers totaled $34,000. One employee charged $26,000 in lodging, without being able to provide any record of the stay. Another charged more than $1,200 for a rental car without receipts.

One traveler was overpaid by more than $3,200 for a 6-month trip because he improperly charged per diem expenses, and yet another traveler on a long trip was reimbursed $2,000 above his rental costs.

Another employee appeared to be compensated twice for five work days and three vacation days. Fifteen others filed vouchers without receipts, most of them for airfare and hotels.

The employees authorized for auto-approval use the feature for most of their travel, according to the IG report, even though the federal travel regulation require employees to get approval except for emergency travel.

BLM and OSM supervisors routinely approve expense reports that don't match receipts or pre-trip approvals.

Supervisors also routinely approve expenses flagged by GovTrip's automatic audit system, including travel without receipts. The system flagged nine of the 99 GovTrip vouchers the IG reviewed. One employee's justification for a questionable report, instead of receipts, was a one-word email response: "OK."

OSM employees didn't submit as many problematic statements as BLM travelers, but 24 of the 90 statements the IG reviewed didn't match receipts, or didn't have receipts at all.

In response to the report, both BLM and OSM said they would limit self-approval to emergency travel. DOI is switching to a new travel system in November.

DOI is not the only federal agency whose employees can approve their own travel. Until last year, NASA had an "inordinate" number of employees not only approving their own pre-travel booking, but their own expense reports as well, according to a February 2012 report by the NASA IG. At least 42 employees were allowed to approve their own travel expenses.

"The number of self-approvers at NASA is exorbitant when compared with other federal agencies such as the Department of Justice where only 2 positions out of more than 116,000 employees have this type of authority," the IG wrote.

NASA employees were reimbursed about $552,000 between October 2009 and December 2010, none of which was reviewed by a higher official.

A NASA spokesman said the agency reduced the number of self-approvers to comply with the IG's recommendation, but would not disclose how many employees continue as before.

Other agencies still allow high-level employees to approve their own travel. The Department of Energy allows department heads to auto-approve, according to a department spokesman.

The U.S. Department of Agriculture also allows high-level managers to approve their own travel, which is reviewed post-payment, according to a USDA spokeswoman.

Michal Conger is a member of The Washington Examiner Watchdog investigative reporting team. She can be reached at mconger@washingtonexaminer.com. Interns Gabriella Morrongiello, James Hemphill and Jack Butler contributed research for this report.