(AP) The airport security systems of the future can see through clothes for weapons, sniff a person for explosives and determine what's in a bottle without opening it.

At Orlando International Airport the future is now, as six prototype security systems will begin operation over the next few days. Orlando, one of the world's busiest airports, was chosen in December as the testing ground for next-generation security checkpoint devices.

However, the heightened security may come at a price.

The scanner that can see through clothes leaves nothing to the imagination, and the bomb sniffer also can test for drugs. Both of these systems concern civil liberties advocates.

On Thursday, the Advanced Technology Checkpoint Project made its debut to the media as government leaders looked on approvingly.

"We have to make sure that people feel safe and secure going to our airports," said Orlando Mayor Glenda Hood, chairwoman of the Florida Domestic Security Advisory Panel. "Our businesses depend on it."

Airport security has been one of the nation's top priorities since Sept. 11, when terrorists hijacked four passenger planes and used them as flying bombs.

The tests in Orlando will be run by the National Safe Skies Alliance, a nonprofit organization that evaluates new security devices and reports its findings to the federal Transportation Security Administration.

Tom Jensen, president/CEO of Safe Skies, said the technology at Orlando International is some of the most advanced in the world.

"A few years ago, a whole roomful of machinery had the same kind of power that your little laptop has today," Jensen said. "Same thing's going to happen with all this. We're going to find the equipment easier to install, with lighter weight and taking up less space to do the same job."

The checkpoint will feature six security systems: three for passengers and three for carry-on baggage. Only passengers who volunteer will go through the checkpoint.

One system, the Rapiscan Secure 1000, uses low-energy X-rays to search a person through clothing. When Rapiscan project manager Bryan Allman scanned himself, a plastic knife hidden in his shirt pocket was detected.

However, the outline of his body - every inch of it - also was clearly visible. Mindful of the machine's revealing nature, airport officials refused to put a woman in the scanner.

Security officials said the scanner would only be used when a passenger shows an "anomaly." Also, the security worker examining the scan would be the same sex as the person being searched.

The potential for complaints about the invasiveness of the search didn't seem to bother Allman.

"Everybody has to learn that the world has changed since Sept. 11, and the world needs a much more thorough type of screening," Allman said.

But the American Civil Liberties Union says the scan is too intrusive.

"This, of course, is a virtual strip-search," ACLU associate director Barry Steinhardt said. "There's no question this has tremendous potential for embarrassment."

Steinhardt pointed out there have been incidents across the nation where male security workers harassed female passengers during hands-on searches.

"We fear this is going to be indiscriminately used," Steinhardt said. "We know that even less-invasive searches are being abused at airports."

Another system, a little larger than a phone booth, blows quick bursts of air at a person, then "sniffs" the air to detect any traces of explosives. The Barringer Ionscan 400B has a library of 40 types of explosives against which it can judge results.

The Ionscan also can be quickly adjusted to test for 60 types of drug residue, which Hood praised as a bonus stemming from the war on terrorism. "The ability to use technology to be able to stop some of the drug trafficking, we're always looking for the opportunity to deal with that war as well," Hood said.

But Steinhardt asked: "Do we really want to be turning airport security personnel into the DEA?" He added that searching for drugs would distract checkpoint workers from their true purpose: keeping planes safe.

Jensen said Safe Skies won't determine whether a security system is too invasive, saying that was a policy question to be decided by the government.