A U.S. consulting firm is charging General Motors (GM.UL)' bankruptcy estate $23 million for 90 days' work, documents indicate.

A quarterly report filed last week in U.S. Bankruptcy Court show the crisis management firm AP Services LLC charged the GM estate for airfare, hotels, meals, rental cars and other expenses, The Detroit News reported Sunday.

The newspaper said the firm is headed by Al Koch, who also serves as the chief restructuring officer of GM's bankruptcy estate. The documents showed he and his 153-member team charged $835 an hour in June for their services. A spokesman for Koch declined comment to the News.

The filing showed AP Services' charges included $455,000 for Koch and more than $108,000 for a paraprofessional. The News said the firm came under fire from the U.S. Justice Department's bankruptcy court monitor, who asserted AP Services' rates were so high they were threatening to suck up funds meant to cover claims against GM.