UK: 'July 7 bombers triggered blasts themselves'

The four terrorists involved in July 7 London bombings, which claimed 56 lives triggered the blasts themselves by pressing a device similar to a button, senior British police sources have claimed, rejecting suggestions that the men were duped into carrying the rucksack bombs.

The "breakthrough" in the investigation discredits the theory that the four British-born men who carried the rucksack bombs on to three crowded tube trains and one bus were unaware they were going to explode, the Guardian newspaper reported quoting sources on Wednesday.

Initially it was thought the bombs might have been attached to devices on mobile phones, a method used in the Madrid bombings to devastating effect. The news that the bomb attacks were carried out with button-like devices triggering the bombs was confirmed by several separate senior police and counter-terrorism sources, the paper said.

• The London Blasts

In the failed attacks on July 21, where the bombs were recovered largely intact, the devices were also to be "manually activated", sources said.

Former anti-terrorism squad bomb expert Tony Dedman said, "It could be a positive push switch, where you push it and the bomb explodes, or a dead man's switch where you push it in and it won't go off until you release it."

• Also read: July 7 London blasts mastermind held in Zambia

The remains of the four July 7 bombers are still being held by police and are still being subjected to forensic tests. Shehzad Tanweer, Mohammad Sidique Khan, Hasib Hussain and Jermaine Lindsay died in the attack, as well as their 52 victims and 750 others who were injured.