Story highlights The financial errors last year hit nearly $7 billion

The Army disputed some of the report's findings

(CNN) The US Army made trillions of dollars of accounting mistakes and often did not have the receipts or invoices needed to support figures in its budget, according to a scathing Pentagon report.

The audit, conducted by the Defense Department's Office of Inspector General, found that the Army erroneously made $2.8 trillion in adjustments in the third quarter of 2015 to its Army general fund - one of the main accounts used to fund the service. The error amount skyrocketed to $6.5 trillion for all of last year, the report said.

The June report, first disclosed by Reuters on Friday, found "unreliable" data was used to prepare the financial statements, leading to the possibility that the Army's finances were "materially misstated."

Financial managers from the Pentagon and the Army "could not rely on the data in their accounting systems when making management and resource decisions," the audit said.

An Army spokesman disputed some of the findings.

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