Details of a Pentagon audit released Wednesday show a contractor hired to train Afghan security forces bought luxury vehicles, alcohol, and prohibited automatic weapons while making lavish overpayments to staff.

Sen. Claire McCaskill, D- Mo., published the Defense Contract Audit Agency findings of $50 million in questionable expenditures by New Century Consulting and asked Defense Secretary Jim Mattis to explain by Aug. 28 who was responsible for oversight of the contractor. She also wants to know what the Pentagon is doing to reclaim the costs.

New Century was hired as the prime contractor in 2013. McCaskill said another DCAA audit on the more recent expenses is ongoing and results are expected next year. When contacted by the Washington Examiner, New Century Consulting said it would be inappropriate for the company to comment on an ongoing matter.

"Whoever approved of this spending should be fired — it's a slap in the face to Missouri taxpayers and the entire contracting process," McCaskill said in a released statement. "I'm going to get to the bottom of what happened with this contract and why a company with so many previous problems keeps getting contracts."

The purchases of Porsches, an Alfa Romeo, a Bentley, an Aston Martin, and a Land Rover occurred while the company was a subcontractor between 2008 and 2013 on a program to mentor Afghan security forces on collecting intelligence, according to McCaskill. It provided no documentation to justify the expenses.

"NCC admitted to using the cars on non-working hours without keeping adequate records of the non-work use," McCaskill wrote in a letter to Mattis on Tuesday.

The audit found the company also hired "significant others" as executive assistants with average annual salaries as high as $420,000, spent $1,500 on alcohol, and paid $42,000 in cash for automatic weapons that were prohibited under its contract, according to McCaskill.

Most of the company's work was done by consultants who trained Afghan forces and it continued to pay those employees full salaries instead of the contract-required 60 percent of pay while they were on leave, ringing up excessive payments of $15 million, auditors found.

The Pentagon spent $458 million on the Afghan intelligence training program but a lack of oversight made it difficult to measure whether the effort led to any improvements in the country's operations, according to a report released last month by the Special Inspector General for Afghanistan Reconstruction.