WASHINGTON — As the busy Thanksgiving travel weekend approaches, government officials went on the offensive Monday to quell passenger complaints about full-body scans and aggressive pat-downs at airports, saying the hype swirling around a few highly publicized cases does not reflect the reality of the new safety inspections.

In the first two weeks after the enhanced screening measures began on Nov. 1, the Department of Homeland Security said that about 700 of an estimated 28 million airline passengers lodged a complaint with the Transportation Security Administration.

Of the passengers asked to submit to a full-body scan, only 1 percent have opted out and instead agreed to a pat-down, which includes TSA agents using their hands to search passengers’ clothed genital areas.

The TSA also released a public service announcement Monday with advice for travelers, emphasizing that the pat-downs are rare – only 3 percent of all airline passengers have had one – and that travelers can request that they be done in a private room.

Transportation Security Administration chief John Pistole said Monday that he disregarded internal advice and decided not to tell the public in advance about aggressive new screening and pat-down procedures for airline passengers, fearing terrorists could try to exploit the information.

In an hour-long discussion with reporters, Pistole said media officials at the Department of Homeland Security had urged him to “get out ahead” of the potential controversy by formally announcing plans for enhanced body searches and the use of new X-ray and radio-wave imaging devices at 70 airports beginning in November.

But doing so would have provided a “roadmap or blueprint for terrorists” to avoid detection by using other airports where the new technology wasn’t in place, Pistole said.

Rather than publicize the changes, Pistole said he made a “risk-based” decision to roll it out first and “try to educate the public after we did that.”

The result has been a firestorm of criticism from lawmakers and passengers who claim the technology and aggressive searches are unnecessary, intrusive and a violation of their privacy rights.

The protesters found some sympathetic listeners on Capitol Hill. Sen. Olympia Snowe, R-Maine, sent Pistole a letter requesting information about the training TSA officers received before the pat-downs began.

A loose network of groups opposed to the new rules are urging air travelers to “Opt Out” of advanced full-body imaging machines on Wednesday – the day before Thanksgiving – in an effort to create delays in security lines. TSA officials said they will have extra workers on duty to deal with any slowdowns.

Most passengers will continue to pass through metal detectors only and will not get a full-body scan or a pat-down, officials said.

Despite the stepped-up public relations effort, the government was still facing formidable opposition in the form of Internet videos that have gone viral in the past few days.

In one video, TSA agents at the Salt Lake City airport were performing a pat-down on a young boy when his father opted to remove the boy’s shirt.

In a widely seen YouTube clip, John Tyner warns agents not to “touch my junk” as he refused to submit to either a full-body scan or a pat-down screening.

An ABC News/Washington Post poll released Monday found that Americans support the use of full-body screening machines by a 2-to-1 margin, but were evenly divided about pat-downs. Sixty-eight percent of respondents said it was more important to investigate possible terror threats than to protect personal privacy.

Pistole said his agency is constantly working to “blend privacy and security,” responding to travelers’ concerns while still confronting threats like that of the Christmas Day bomber in 2009 — when a Nigerian man was able to board a plane carrying PETN, a powdered explosive, that he hid in his underwear as he passed through a metal detector. Pistole said the new guidelines were developed to address that specific vulnerability in airport screening.

“Everyone on a plane wants to know that the person next to them has been screened yet everyone wants their privacy as well,” Pistole said.

TSA uses two types of scanners. In terms of radiation exposure, the energy projected by the type of scanner using millimeter wave technology is thousands of times less than a cell phone transmission, while a single scan using backscatter technology produces exposure equivalent to two minutes of flying, according to DHS. The scanners do not store images.