London attacks: Were mobiles used to detonate bombs?

With parallels already being drawn between Thursday's terrorist attacks in London and 2004's Madrid train bombings, mobile phones are being labelled as key weapons in the terrorist's armoury.

The role that such devices played in the Madrid bombings, which left almost 200 people dead in the Spanish capital, is well documented: 10 bombs were attached to mobile handsets, with the phones' alarms used to detonate the explosives. Now security experts and worried commuters are asking if the pattern has been repeated in the London attacks.

A spokeswoman for Scotland Yard told silicon.com that the role of mobile handsets in the bombings might yet be examined. "We haven't ruled out any area of investigation," she said.

While the use of mobile phone alarm functions as detonators has yet to be discounted, the possibility of mobiles being harnessed to set off the bombs remotely - over a network - seems to have been ruled out.

In a press conference earlier today, DCC Andy Trotter of the British Transport Police indicated that the use of mobiles to detonate devices seems highly unlikely given the lack of network coverage across the London Underground network.

"We all know that parts of the Tube can get a signal," he said. "But there are parts… where that is most unlikely." Trotter cited the example of the Piccadilly line - where the second bomb went off - as one area where mobile networks are unable to provide coverage.

Eyewitnesses at the scene of the explosion which tore apart a double-decker bus in the Tavistock Square area have reported seeing a man, believed to be one of the terrorists, repeatedly "diving into" a bag prior to the bombing. No reports have mentioned the use of a mobile.

Also two of the UK's largest mobile operators, O2 and Vodafone, have confirmed that the government did not ask them to shut down network coverage in the capital - one measure which would have prevented a mobile phone signal being used to detonate a device remotely.

A spokesman for network provider Orange declined to comment on the use of mobiles as possible triggers for the explosives but said the operator is "working with the Home Office in any way we can".

The UK's main operators could potentially provide a wealth of information to the police to help trace the individuals responsible for the London terrorist atrocities.

Given the highly co-ordinated nature of the attacks - the four bombs were all detonated within an hour - mobile phones are likely to have been used by the bombers to monitor each other's whereabouts and plan the explosions.

Providing mobiles under suspicion from that time can be identified, information could be gleaned about the bombers from purchase information about handsets or bank details related to credit top-ups for pay-as-you-go devices.

Mobile phone operators will also be able to provide the authorities with information on which of their customers were using their phones in specific areas near where the attacks took place, helping the police and other emergency services both locate potential suspects and identify any victims of the bombings yet to be identified.

Dean Bubley of telecoms research firm Disruptive Analysis told silicon.com that the mobile networks might also be able to offer key information on suspects' locations prior to the attacks.

"There are things that can give more information than just which [mobile network] cell someone is in," he said. "You couldn't do that in real time for everyone - it would take too much computing horsepower - but with a subset of people, you can tell quite a bit."

Bubley added that GCHQ is now likely to be using pattern detection software to identify any unusual behaviour among mobile phone users leading up to the bombings.