(CNN) The Drug Enforcement Administration has paid out more than $800,000 over the last 20 years to an Amtrak employee to act as a confidential source, providing information that would have been readily available to the law enforcement agency through a joint task-force, according to a new report.

Documents submitted to register the Amtrak employee as a confidential source failed to mention the payments for information "that was available at no cost to the government in violation of federal regulations relating to the use of government property, thereby wasting substantial funds," according to a report by the Justice Department's Office of the Inspector General.

The DEA did not respond to CNN request for comment.

The DEA already participates in a joint-task force with the Amtrak Police Department to stop the flow of contraband on the mass-transit system and by directing the confidential source to gather specific information, DEA agents also "exceeded the terms of the Amtrak employee's CS classification," the report says.

The investigation also revealed that this wasn't the only instance, as an Amtrak Police Department officer assigned to work with a DEA task force registered a different Amtrak employee as a confidential source paying out more than $9,000.

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