More than half the federal security force at Orlando International Airport failed a test in June to measure how well the officers detect explosives, guns and other threats at passenger checkpoints, a newspaper reported Wednesday.

A total of 501 people failed a test known as Threat Image Projection in June, according to a Transportation Security Administration memorandum obtained by the Orlando Sentinel. That represents about 60 percent of the airport's 830 security officers.

The test randomly flashes images of explosives or other banned items onto the X-ray screen as carry-on bags are being processed through the machines.

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Officers who consistently fail to recognize dangerous images fail the test and are required to undergo remedial training.

TSA spokesman Christopher White declined to comment Wednesday on any of the numbers cited by the newspaper but said the officers fared better on the test in July. He called the June test results an "anomaly" and noted that the test is just one of many methods used to evaluate officers.

The high number of failures in June was the result of an increased number of new and less-experienced officers on the job, scheduling changes and new, less-familiar threat images on the test, White said.

"The traveling public should be very comfortable with the level of security officers are providing," he said.

The agency also evaluates officers by sending undercover employees through checkpoints with concealed weapons.