WASHINGTON - The Nigerian suicide bomber who allegedly tried to blow up U.S. bound Northwest Airlines Flight 253 on Christmas Day told the FBI that there are more like him in Yemen.

Facing such threats, authorities may use more "body scanners" in airports. While these scanners are already used in 20 U.S. airports, they have drawn some controversy.

The high-tech security scanners have the ability to spot explosive powder - much like the type last Friday's alleged bomber Umar Farouk Abdulmutallab hid inside his underwear.

The whole body imaging machines use low x-ray levels to create a virtual image of passenger's bodies.

"This is important technology to meet the threats that we're facing now," Rapiscan Vice President John Fleming said.

Unlike metal detectors, the machines can spot plastic or chemical explosives affixed to the body.

The reason they're not in every U.S. airport? Privacy concerns.

The machines conduct virtual strip searches revealing the size and shape of a person's body.

In airports where they're already being used, passengers can opt to receive a pat down search by a security officer instead.

In June, the House of Representatives voted overwhelmingly against using the machines for primary screenings. The legislation is still pending in the Senate.

Meanwhile, some security experts predict the machines will soon become more widely accepted.

Former Assistant Secretary of Homeland Security Stewart Baker said, "You are going to learn to live with that just as you learn to live with other things people thought were privacy invasions when they first occurred."