Security and intelligence experts are deeply worried by a new development in suicide bombing. 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 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.

Peter Neuman of Kings College London said the case would 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 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.

Meanwhile, two suicide car bombs killed 16 people and wounded about 150 others in separate attacks in north-western Pakistan yesterday, just days after the Taliban warned suicide strikes were coming if the military pressed forward with an offensive. A third bomb injured four in the restive region.

Pakistan's mountainous, lawless north-west region along the Afghan border – where the government holds little control – is a favoured area for insurgents to plan attacks on US and Nato troops in Afghanistan, as well as on Pakistani security forces and government workers.

A suicide bomb was detonated outside a bank affiliated with the army in Peshawar, the capital of North West Frontier Province, police said. Ten people were killed and 79 wounded, said Sahibzada Mohammed Anis, a senior government official.

"We saw body parts in the car and our investigation confirms it was a suicide attack," said Malik Shafqat, a police official in Peshawar. He said the attacker also threw a hand grenade before detonating the bomb but it did not explode.

A suicide blast also hit a police station in the province's Bannu district earlier yesterday, killing at least six people and wounding nearly 70 others, police said. The Taliban claimed responsibility for that attack. A third bomb exploded in the northern town of Gilgit, wounding four people.

Qari Hussain Mehsud – known for training Taliban suicide bombers – warned of more attacks in an interview at a secret location in North Waziristan on Thursday, just hours before US missiles hit the area and killed 12 people.

"We have enough suicide bombers and they are asking me to let them sacrifice their lives in the name of Islam, but we will send suicide bombers only if the government acts against us," he said in the interview.