Revealed: suicide bombers flew together to Karachi

Records show a third bomber, Hasib Hussain, 18, who blew up the No 30 bus, arrived in Karachi last July on a Saudi Arabian Airlines flight SV-714. His date of departure is not known.

MI5 is investigating reports from the Pakistan security services that the three men from Leeds went to several madrassas - religious schools, some of which are run by terrorist groups.

Mounting evidence points towards Pakistan as the likely source of inspiration and training for the bombers, although the identity of the chief planner and bomb-maker is unknown.

Pakistani intelligence officials have said Tanweer stayed briefly at a madrassa and met a member of an outlawed domestic militant group. Pakistani intelligence agents have questioned students, teachers and administrators at the school in Lahore, and at least two other al-Qa'ida-linked radical Islamic centres.

Pervez Musharraf, the President of Pakistan, said that some Islamic schools were involved in terrorism. His comments came after an intelligence official named one of five militants detained by security forces at the weekend as Qari Usman, a bomb expert from the banned militant organisations Jaish-e-Mohammed (Army of Mohammed). The militants were detained in Faisalabad as part of a crackdown after the London bombings, although no link has been established.

Khan was known to Mohammed Junaid Babar, a terrorist in US custody who pleaded guilty last year to providing material support to al-Qa'ida, two US intelligence officials said. Khan was investigated by MI5 last year but was not deemed to be a terrorist threat.

He was subject to a routine assessment by MI5 because of an indirect connection to an alleged plot to build a lorry bomb in Britain. He was one of hundreds investigated but not considered a risk.

Police are still trying to identify the type of homemade explosive used.

Ministry of Defence experts are examining chemicals and other bomb-making equipment found at a house in Leeds, where the bombs are thought to have been made, and a hire car used by the three Leeds bombers.

Initially, forensic specialists thought the explosive used was a home-made substance, nicknamed "the mother of Satan". The explosive, acetone peroxide, can be produced by following instructions on the internet. But there is now doubt about the nature of the material discovered. The explosives were carried in rucksacks bought from Blacks camping shop in Leeds city centre.

Explosive experts are also continuing to examine two cars used by the bombers and left at Luton train station on the morning of the attacks. The bombers travelled from Luton on the train, before dispersing and setting off the explosives.

A senior security source said: "It will take some time for the forensic investigation to show what explosives were used and in what way."

No completed bombs have been discovered by the police and they have not found any evidence of a second suicide unit.

Forensic analysis has also failed to find timers at the blast sites, suggesting that the bombers detonated the explosives by hand.

Scotland Yard's anti-terrorist branch is still trying to establish the exact movements of the bombers leading up to the London attacks. Officers are examining all possible routes from three of the bombers' homes in Leeds and those for the Jamaican-born Germaine Lindsay, 19, from his home in Aylesbury, Buckinghamshire. They have seized more than 12,000 surveillance tapes, many from motorway service stations, and plan to examine a further 13,000.

i100'Geography can be tough'
newsVideo targets undecided voters
Down time: an employee of Google uses the slide to get to the canteen
businessHow bosses are inventing unusual ways of making us work harder
Alexis Sanchez celebrates after scoring his first goal for Arsenal in the Champions League qualifier against Besiktas
sportChilean's first goal for the club secures place in draw for Champions League group stages
ebooksAn evocation of the conflict through the eyes of those who lived through it
REX/Eye Candy
A photo of Charles Belk being detained by police on Friday 22 August
Arts and Entertainment
Amis: 'The racial situation in the US is as bad as it’s been since the Civil War'
booksAuthor says he might come back across Atlantic after all
In Eternal Sunshine of the Spotless Mind Jim Carrey and Kate Winslett medically erase each other from their memories
scienceTechnique successfully used to ‘reverse’ bad memories in rodents could be used on trauma victims
Arts and Entertainment
Vinyl demand: a factory making the old-style discs
musicManufacturers are struggling to keep up with the resurgence in vinyl
Arts and Entertainment
Singer Pixie Lott will take part in Strictly Come Dancing 2014, the BBC has confirmed
Arts and Entertainment
Dennis Stinchcombe, of Broad Plain Boys' Club in Bristol, by a Banksy artwork, titled 'Mobile Lovers', where the sale and handover have been completed at the Bristol Museum & Art Gallery, where it was on display to the public.
artHuge price will help to keep a 120-year-old youth club in Bristol open
Life and Style
Evan Spiegel, the founder of Snapchat, dropped out of Stanford University just before graduation to develop his app
techAnd yes, it is quite a lot
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

Day In a Page

Israel-Gaza conflict: No victory for Israel despite weeks of death and devastation

Robert Fisk: No victory for Israel despite weeks of devastation

Palestinians have won: they are still in Gaza, and Hamas is still there
Mary Beard writes character reference for Twitter troll who called her a 'slut'

Unlikely friends: Mary Beard and the troll who called her a ‘filthy old slut’

The Cambridge University classicist even wrote the student a character reference
America’s new apartheid: Prosperous white districts are choosing to break away from black cities and go it alone

America’s new apartheid

Prosperous white districts are choosing to break away from black cities and go it alone
Tip-tapping typewriters, ripe pongs and slides in the office: Bosses are inventing surprising ways of making us work harder

How bosses are making us work harder

As it is revealed that one newspaper office pumps out the sound of typewriters to increase productivity, Gillian Orr explores the other devices designed to motivate staff
Manufacturers are struggling to keep up with the resurgence in vinyl records

Hard pressed: Resurgence in vinyl records

As the resurgence in vinyl records continues, manufacturers and their outdated machinery are struggling to keep up with the demand
Tony Jordan: 'I turned down the chance to research Charles Dickens for a TV series nine times ... then I found a kindred spirit'

A tale of two writers

Offered the chance to research Charles Dickens for a TV series, Tony Jordan turned it down. Nine times. The man behind EastEnders and Life on Mars didn’t feel right for the job. Finally, he gave in - and found an unexpected kindred spirit
Could a later start to the school day be the most useful educational reform of all?

Should pupils get a lie in?

Doctors want a later start to the school day so that pupils can sleep later. Not because teenagers are lazy, explains Simon Usborne - it's all down to their circadian rhythms
Prepare for Jewish jokes – as Jewish comedians get their own festival

Prepare for Jewish jokes...

... as Jewish comedians get their own festival
10 best cycling bags for commuters

10 best cycling bags for commuters

Gear up for next week’s National Cycle to Work day with one of these practical backpacks and messenger bags
Kate Bush, Hammersmith Apollo music review: A preamble, then a coup de théâtre - and suddenly the long wait felt worth it

Kate Bush shows a voice untroubled by time

A preamble, then a coup de théâtre - and suddenly the long wait felt worth it
Robot sheepdog technology could be used to save people from burning buildings

The science of herding is cracked

Mathematical model would allow robots to be programmed to control crowds and save people from burning buildings
Tyrant: Is the world ready for a Middle Eastern 'Dallas'?

This tyrant doesn’t rule

It’s billed as a Middle Eastern ‘Dallas’, so why does Fox’s new drama have a white British star?
Rachael Lander interview: From strung out to playing strings

From strung out to playing strings

Award-winning cellist Rachael Lander’s career was almost destroyed by the alcohol she drank to fight stage fright. Now she’s playing with Elbow and Ellie Goulding
The science of saturated fat: A big fat surprise about nutrition?

A big fat surprise about nutrition?

The science linking saturated fats to heart disease and other health issues has never been sound. Nina Teicholz looks at how governments started advising incorrectly on diets
Emmys 2014 review: Can they genuinely compete with the Oscars

Can they genuinely compete with the Oscars?

The recent Emmy Awards are certainly glamorous, but they can't beat their movie cousins