Thousands of holiday travelers are likely to be greeted by long lines at the security gates at airports across the country.

But a new study suggests the extra security measures the Transportation Security Administration adopted in recent years in an attempt to beef up security have not made air travel any safer.

The study conducted by a team at the Harvard School of Public Health found no evidence that making travelers take their shoes and belts off at security checkpoints or banning large containers of liquid items actually prevented any incidents.

The study, which was reported in the British Medical Journal, concluded there is no evidence that the measures actually increase the safety of the passengers.

"Can you hide anything in your shoes that you cannot hide in your underwear?" the researchers asked in the report.

The TSA has defended its practices, saying more than 13 million prohibited items were confiscated in one year alone.

But the researchers noted that most of the confiscated items were lighters, and said the TSA implemented the new security measures haphazardly without first evaluating their effectiveness.

"We noticed that new airport screening protocols were implemented immediately after news reports of terror threats," the researchers wrote.

The study did not focus on other screening methods such as x-ray machines and explosive detection.

A TSA spokesman was not immediately available for comment.