Airport travelers call it groping, prodding or just plain inappropriate - a pat-down that probes places where the sun doesn't shine. The Transportation Security Administration calls it the new reality of airport security.

Following the uncovering of a terrorist plot last month to blow up cargo planes en route to the United States, the TSA has instituted a new type of pat-down of passengers, a move that's part of a general tightening of air security. If a full-body scanning machine shows something strange or a passenger declines to go through the machine - which is now in use in the Washington region's three major airports - an officer will perform a more personal search.

The examinations routinely involve the touching of breasts and genitals, invasive searches designed to find weapons and suspicious items. The searches, performed by TSA security officers of the same sex as the passenger, entail a sliding hand motion on parts of the body where a lighter touch was used before, aviation security analysts say. The areas of the body that are being touched haven't changed.

"There's nothing punitive about it; it just makes good security sense," the TSA said via its blog. "And the weapons and other dangerous and prohibited items we've found during pat-downs speak to this."

But the new pat-downs have prompted a growing backlash among pilots and flight attendants, civil liberties groups and security-weary passengers who say the touching goes too far.

"It's more than just patting you down. It's very intrusive and very insane. I wouldn't let anyone touch my daughter like that," said Marc Moniz of Poway, Calif., who is planning to accompany his daughter's eighth-grade class from San Diego to Washington in April. "We're not common criminals."

In the latest escalation of the debate over the balance between security and passenger rights, privacy advocates have enlisted consumer rights activist and four-time presidential candidate Ralph Nader, who called the screening techniques "extremely voyeuristic and intrusive."

"If anyone is going to try to get through, they're going to [conceal items in body cavities], so this isn't going to stop that," Nader said. "My prediction is that TSA is going to lose all of this."

Brian J. Sodergren of Ashburn, who works in the health-care industry, is organizing an "opt out" day to encourage passengers to say no to advanced imaging technology, known to industry insiders as a "virtual strip search." He's planning the protest for one of the busiest travel days of the year - Nov. 24, the day before Thanksgiving.

"Many people only fly around the holidays and may not be aware of the security changes," Sodergren said. "I think once people are made aware of what is happening, they may have reservations about the new procedures."

Another group launched a Web site, WeWontFly.com, and says it has gotten more than 70,000 hits per day since going online a week ago. The Web site asks passengers to say no to scans and pat-downs and for TSA to remove its "porno-scanners" and "gropers."

"We're opposed to letting TSA treat us like criminals," said James Babb of Eagleville, Pa., an activist who is organizing the We Won't Fly campaign.