The US government is warning airlines that terrorists are considering having bombs surgically implanted inside themselves.
Passengers may have to undergo even more strict security checks, especially when flying to the US.
The FBI and Homeland Security Department has sent a memo to security officials about "body packing," describing it as a "criminal tactic with possible terrorist application".
The memo cited a 2005 incident in which Colombian men were accused of surgically implanting narcotics into human couriers.
Bombs-in-the-body is not a new idea, but recent intelligence indicates a fresh interest in using this method.
People-scanning machines in airports are not able to detect explosives hidden inside humans.
There is no current information that points to a specific plot involving surgically implanted explosives, a US security official said.
As airport security has increased since the September 11, 2001, terror attacks, so has the terrorists' creativity in developing methods to get around it.
Aviation continues to be a special target, and evidence from Osama bin Laden's compound showed that the al Qaida leader retained his fascination with attacking aircraft until his death in May.
The US government has been working with foreign air carriers and governments to identify ways to discover hidden explosives, including bombs potentially hidden inside of humans.
Officials did not want to discuss specific security measures under consideration.
Once a terrorist finds a willing suicide bomber, secures the explosive material and makes the bomb, carrying off this tactic is not that difficult, said Chris Ronay, a former chief of the FBI explosives unit.
"It's rather easy and the damage could be rather severe," Ronay said.
Surgery to implant explosives could be done a couple of days before a planned attack, said James Crippin, an explosives expert in Colorado.
But Jimmie Oxley, a chemistry professor at the University of Rhode Island and explosives expert, said it would be tough to carry out such an effort successfully. She said there are only so many places to hide a bomb in the body, and a suicide bomber would have to recover enough from the surgery to travel and set off the device.
Transportation Security Administration spokesman Nick Kimball said, passengers flying into the US may notice additional security. "Measures may include interaction with passengers, in addition to the use of other screening methods such as pat-downs and the use of enhanced tools and technologies."