Security and intelligence experts are deeply worried by a new development in suicide bombing, the BBC has learned.
It has emerged that an al-Qaeda bomber who died last month while trying to blow up a Saudi prince in Jeddah had hidden the explosives inside his body.
Only the attacker died, but it is feared that the new development could be copied by others.
Experts say it could have implications for airport security, rendering traditional metal detectors "useless".
Last month's bombing left people wondering how one of the most wanted al-Qaeda operatives in Saudi Arabia could get so close to the prince in charge of counter-terrorism that he was able to blow himself up in the same room.
Western forensic investigators think they have the answer, and it is worrying them profoundly.
The explosives, they believe, were detonated by mobile phone.
Peter Neuman of Kings College London says the case will be studied intensively, and that there are "tremendous implications for airport security with the potential of making it even more complicated to get on to your plane".
"If it really is true that the metal detectors couldn't detect this person's hidden explosive device, that would mean that the metal detectors as they currently exist in airports are pretty much useless," he said.
The bomber was a Saudi al-Qaeda fugitive who said he wanted to give himself up to the prince in person.
The prince took him at his word and gave him safe passage to his palace.
But there, once he got next to his target, the bomb inside him was detonated.
Miraculously the prince survived with minor injuries, but footage emerging this week shows a sizeable crater in the concrete floor and the bomber's body blown in half.
It is believed the force of the blast went downwards which is why only the bomber died.