Technology exists that might have detected explosives hidden in the underwear of a Nigerian man accused of trying to blow up a plane over Detroit, but cost and privacy worries have until now prevented its widespread use.

Umar Farouk Abdulmutallab, 23, is suspected of trying to ignite an explosive called PETN using a chemical-filled syringe as the Delta Air Lines flight approached Detroit on Christmas day.

He had passed through security checks in Lagos and Amsterdam, where standard metal detector archways failed to spot his weapon.

Amsterdam’s Schiphol Airport has at least 15 full-body “millimetre wave” scanners that see underneath passengers’ clothes to detect suspicious packages or weapons.

The problem: their use has been only voluntary because of concerns that the scans reveal passengers “naked” to the operators and anyone else passing by the machine’s screen.

The costs are also substantial. Whereas a traditional archway metal detector costs up to $15,000, more intensive whole-body scanners cost about 10 times as much.

“I don’t anticipate myself that there’ll be a rush to buy new equipment because airport operators are strapped for cash at the moment and the equipment itself, whilst good, is not a solution to the problem,” said Kevin Murphy, product manager of physical security for Qinetiq Group, a British-based defence and security technology group.

“Some passengers are reassured that there’s new technology there and are prepared to give up some measure of their privacy for it, and others have been outraged by it.”

Airport operators need effective security plans, behavioural modelling and hiring processes just as much as they need advanced hardware, he said. Qinetiq is focusing its efforts on “standoff screening” that scans passengers even before they reach security checkpoints.