Lines at London's Heathrow Airport are "much longer than usual at this time of the year" because of fears that Al Qaeda terrorists have developed explosives that can be implanted in people, The Mirror reports.
Body scanners can detect items that people are carrying with them, but they aren't able to catch devices that are inside of the body.
Heathrow Airport is reportedly concerned about women suicide bombers who conceal explosive materials inside breast implants.
Explosives specialists told The Mirror that these makeshift bombs could possibly be set off by an electrical trigger or by injecting another liquid into the implant.
U.K. officials reportedly have "credible intelligence" that terrorists are plotting attacks on airplanes flying out of London, and security staff have been told to "pay particular attention to females who may have concealed hidden explosives in their breasts," an airport staff member told The Mirror.
As a result, security staff at Heathrow are taking longer to scan people.
An airport official told The Mirror that Heathrow doesn't comment on "specific security measures," but a staff member said security is being beefed up and it's taking longer to get through lines.
The idea that terrorists are being trained to plant bombs inside of people isn't new. NBC News reported in 2012 that Western intelligence agencies are concerned that Al Qaeda doctors are being trained to implant these explosives into breasts and abdomens.
And earlier this month, ABC News quoted a senior U.S. intelligence official saying the government is concerned about surgically implanted devices that can avoid detection methods.