The Secret Service faced another embarrassing episode after a government revealed two officers were found sleeping on the job.

The revelation occurred during an audit by the Department of Homeland Security, which oversees the Secret Service. The latest in a string of embarrassments to tarnish the agency's reputation is now raising concerns that employees are being overworked, reports CBS News correspondent Jeff Pegues.

In a "management alert" from Inspector General John Roth to Secret Service Director Joseph Clancy, federal auditors says they "observed two officers sleeping at their posts" on August 11, 2015.

One officer was assigned to the White House, and the other, reportedly to the Israeli embassy.

The inspector general cites the agency's "staffing and scheduling" as contributing to officer fatigue, noting one of the officers worked"almost 60 hours of overtime" over a two-week period that included President Obama's trip to Kenya in July.

"They're worked fourteen hours a day, no days off for months on end -- totally absurd -- leading to great turnover, poor morale," said Ronald Kessler, who has written extensively about the Secret Service.

The Secret Service disputes the inspector general's findings, arguing that "the officers had sufficient days off prior to the incident."

But the agency did say there's no excuse for the officers' misconduct and that both have been disciplined.

The audit stemmed from a previous Secret Service blunder when a fence-jumper got inside the White House last year.

Other public problems to plague the agency include a 2012 prostitution scandal in Colombia and a pair of agents -- reported to be "likely" intoxicated -- who crashed through a White House security barrier last March.

One of the two officers disciplined in the latest scandal to rock the agency admitted to taking cold medicine prior to working. While Secret Service officers are technically working during the president's trips, they have no protective mission during flights and tend to rest.

Clancy - who was permanently appointed to lead the agency back in February - has pledged to improve staffing and training.