Responding to the public rancour over tough new airport security checks, the American transportation security chief is urging travellers to grin and bear it -- or face lengthy delays.

Under the Transportation Security Administration's latest rules, travellers at some airports must step through an X-ray scanner that performs a virtual full-body strip search. Although the human screener sits in a different room, does not see discernible faces and does not know the individuals' identities, the extent of the scan has left some reluctant.

The fact that the alternative is a pat-down that includes agency officials touching the passenger's clothed genital areas -- or simply not flying at all -- has further fuelled the debate among would-be air travellers.

Tom Sawyer, a bladder cancer survivor from Michigan, was left in tears after a security agent at a Detroit airport gave him such a rough pat-down that it broke the bag he wears to collect his urine, which spilled all over his clothes.

"I was so embarrassed and so petrified (of) going out into the airport thinking people would see me and, quote-unquote, smell me," Sawyer said.

Sawyer received an apology. However, an Internet campaign -- sparked by San Diego traveller John Tyner who infamously told a TSA screener, "If you touch my junk, I'm gonna have you arrested" -- has grown against the procedure, urging travellers to refuse the pat-downs on Nov. 24, the day before U.S. Thanksgiving. That is typically the single busiest travel day in the United States.

In the wake of this latest backlash, U.S. President Barack Obama said on Saturday that the TSA must ensure it is operating with people in mind.

"You have to constantly refine and measure whether what we're doing is the only way to assure the American people's safety," Obama said. "And you also have to think through, are there ways of doing it that are less intrusive."

Commenting on CNN's "State of the Union" on Saturday, Transportation Security Administration head John Pistole insisted the threat is too great for him to back down.

"No, we're not changing the policies," Pistole said.

But just hours later, he issued a statement saying the agency would work to make screening methods "as minimally invasive as possible."

It was that message Pistole took to the airwaves Monday morning. In a series of media interviews, the TSA chief said he understood many people's reluctance to submit to the security procedures. With one of the country's busiest travelling days fast approaching, he said anyone who decides to boycott the body scans would only serve to delay people trying to go home to their loved ones.

"We're going to look at how can we do the most effective screening in the least invasive way knowing that there's always a trade-off between security and privacy," he told NBC's "Today" show.

"What I'm doing is going back and looking at, are there less invasive ways of doing the same type of screening?" Pistole said on ABC's "Good Morning America."

But any of the 24 million people expected to travel over the Thanksgiving period who might be expecting Pistole to change the rules shouldn't hold their breath.

"In the short-term, there will not be any changes," Pistole told CNN.

Homeland Security Director Janet Napolitano and other White House officials conceded Monday that the implementation of the latest stepped-up security measures has been less than perfect.

But Napolitano reminded travellers that it was during Christmas, another busy holiday period, last year that Umar Farouk Abdulmutallab tried to blow up an airliner with explosives hidden in his underwear, which metal detectors did not catch.

Ginger McCall, a civil liberties lawyer, said travellers have been left wondering how many more security rules they will be required to follow. In the wake of the Sept. 11, 2001 terrorist attacks on the United States, box cutters and other sharp objects were banned from carry-on luggage. Over the years, liquids were restricted and shoes became search targets after various failed airline bombings.

"If the terrorists start smuggling in explosives in body cavities, are we going to have to start submitting to full body cavity searches?" McCall wondered.

Stepping through an electronic body scanner can take as little as 10 seconds. Because full pat-downs take considerably longer, officials worry a widespread boycott could cause a cascade of delays at dozens of major airports across the U.S.

Meanwhile, Canadian officials have taken note of the controversy south of the border. Transportation Minister Chuck Strahl told the House of Commons Monday that he is reviewing airport screening procedures with the Canadian Air Transport Security Authority. According to the CATSA, only those passengers selected for secondary screening are subjected to a full-body scan or a pat-down.

During a one-year period, CATSA data shows, 1,500 passengers of the 48 million screened issued formal complaints, most of which were quickly settled by the agency's review process.

With a report from CTV's Joy Malbon