A federal watchdog told Congress on Tuesday that a recent covert audit of U.S. airports found layers of security were “simply missing,” in the latest undercover investigation to expose gaps in Transportation Security Administration procedures. 

The findings were revealed by Department of Homeland Security Inspector General John Roth during a House hearing on TSA problems where new Administrator Peter Neffenger also testified on what he's doing to fix them. 

Roth said the tests by federal auditors found "troubling" problems related to technology, procedures and human error at security checkpoints. He said the findings were “consistent across every airport.”

However, he also said new TSA leadership promptly began addressing some of the issues and he is optimistic about airport security being improved.

“I am hopeful that the days of TSA sweeping its problems under the rug and simply ignoring the findings and recommendations … are coming to an end,” he told the House Committee on Oversight and Government Reform.

The inspections were conducted at eight airports. Roth said he was limited in talking about specifics because the findings of the report, which he gave to Congress in September, are classified.

The TSA was created in 2001 in the immediate aftermath of the 9/11 attacks in which terrorists hijacked four U.S. passenger jets, slamming one into the Pentagon and two into the World Trade Center towers, killing nearly 3,000 people.

The agency has since faced widespread criticism about security lapses at passenger checkpoints, at baggage screening facilities and on flights, amid efforts to protect air travelers around the world. The previous acting head of the TSA was reassigned earlier this year after an IG review found undercover agents were able to sneak fake explosives and banned weapons through checkpoints. 

Neffenger, a retired Coast Guard admiral who then took over at TSA in July, vowed on Tuesday to “never take his focus off improving the system.”

He also said he was “greatly disturbed” by the findings and has since met several times with Roth to better understand the failures and the scope of the corrective actions needed.

“My immediate priority for TSA is determining root causes and implementing solutions,” Neffenger also said.

Still, committee Democrats and Republicans were skeptical. 

Rep. John Mica, R-Fla., called Neffenger a “true hero” but said the report findings were “alarming” and acknowledged, “I don’t care what I’ve heard today, I’m convinced the system cannot be fixed.”

Maryland Rep. Elijah Cummings, the top Democrat on the GOP-led committee, said the TSA is “responding with urgency” but the work is “far from complete.”