Explosive used in London attacks can deteriorate 'after a few days'

THE homemade explosive thought to have been used in both London bombing waves can deteriorate after just a few days.

The short shelf-life of the substance, acetone peroxide, leaves open the possibility that the explosives in both the July 7 bombings and yesterday's attempts came from the same batch.

It is a favoured weapon of suicide bombers in the Middle East, where it is known as Mother of Satan.

The four unexploded devices may provide a wealth of clues to the identities of those behind the latest bomb attacks in the capital.

Counter-terrorist experts believe the failure of the bombs to explode could uncover fingerprint and DNA evidence.

Examination of the devices could also establish if the explosives were similar to the ones found in West Yorkshire after the July 7 suicide bombings.

Andy Oppenheimer of Jane's Information Group said: "If this is the same material in both attacks, it can deteriorate and may have lost its function. It is an explosive that has to be used quickly after it is made. There is a possibility that that is what has happened here - rather than the detonators failing it is the actual explosive mixture that has failed. It loses its qualities over time and deteriorates in such a way that it's not very useful as an explosive any more."

He said acetone peroxide can begin to lose its explosive qualities within "a few days".

Mr Oppenheimer added: "They probably have tried to rush to make some more devices and get them deployed as quickly as possible. People associated with al-Qaida have always tended to use cheap, quick materials to carry out their destruction."

Three of the four devices used this week were thought to be of a similar size and weight to the bombs used in the July 7 attacks. The fourth was smaller and appears to have been contained in a small plastic box.

It was believed that on three of the devices the detonators went off but the bomb failed to explode. On the fourth it was thought the detonator itself failed.

Acetone peroxide is made from common household items - sulphuric acid, hydrogen peroxide and acetone - and is known scientifically as triacetone triperoxide or TATP.

Would-be "shoebomber" Richard Reid used acetone peroxide and plastic explosive packed into his basketball shoes.

Timeline

July 7

Thursday morning: Suicide bombers Husab Hussain, 18, Shehzad Tanweer, 22, and Mohammed Sadique Khan, 30, drive from Leeds to Luton.

7.40am: They meet up with Lyndsay Germaine, 19, and all four board a train from Luton to King's Cross station in London.

8.30am: In London, they fan out from the station, with Tanweer taking the Circle Line east, Khan the Circle Line westbound, and Germaine heading south on the Piccadilly Line.

8.50am: Three bombs explode within a minute on London Underground trains.

The first explosion is near Aldgate on a train travelling towards Liverpool Street. The explosion occurs 100 yards into the tunnel. Seconds later, a bomb explodes in a train near Edgware Road. Another goes off at almost exactly the same time in the first carriage of a train between Russell Square and King's Cross.

9.47am: Hussain detonates his bomb in Tavistock Square after leaving the Underground and boarding the No 30 bus, killing himself and more than 20 others. More than 50 people died in the four incidents.

10.21am: Scotland Yard confirms there have been "multiple explosions" in London.

11am: Members of the public are told not to travel to London.

11.52am: All London hospitals are full, police confirm.

Midday: British Prime Minister Tony Blair confirms an unknown number of people have died and others have been seriously injured in a series of "barbaric" terrorist attacks.

July 21

12.25pm: Police evacuate Shepherd's Bush Tube station following an attempt to set off an explosion.

12.30pm: Emergency services called to Oval Tube station. About 30 passengers are evacuated saying that they had seen "white smoke". There are also reports of a man dumping a rucksack in a carriage then fleeing.

12.45pm: Ambulances sent to Warren Street Tube station after reports of a rucksack exploding on a train in a tunnel just outside the station.

1.30pm: The driver of the No 26 bus reports hearing a bang followed by a smell of smoke coming from the upper deck while driving along Hackney Road, Shoreditch. Upstairs windows are blown out.

5.30pm: Metropolitan Police Commissioner Ian Blair confirms there were four explosions or "attempts" at explosions across London, with three at Underground stations and one on a bus. He says the devices failed to explode properly, no one was killed and there was one confirmed casualty.

Yesterday

10am: A man thought to be a suspected suicide bomber is shot by armed police officers as he tries to flee on an Underground train at Stockwell tube station in south London.

10.30am: Witnesses report that up to 20 undercover officers chased the Asian man - possibly one of the suspects from Thursday's blasts - into the south London station.

It is said he was shot up to five times after running on to a Northern line train waiting at the platform.

10.42am: Police cordon off the area around the station and services are suspended on the Victoria and Northern lines.

10.55am: Scotland Yard confirms officers have shot a man.

11am: Armed police reported to have surrounded a mosque in east London.

11.50am: Scotland Yard confirms the man shot at Stockwell station died at the scene.

1.10pm: The Muslim Council of Britain demands a police explanation for why the man - described as Asian in appearance - was shot dead at Stockwell station.

A spokesman says Muslims are nervous that police may have a "shoot to kill" policy in force in the wake of the attacks.

2.55pm: Detectives and armed police search an address in the Harrow Road area of West Kilburn in connection with Thursday's attempted bombings, Scotland Yard say.

4.30pm: Armed police arrest a man after storming on to an estate near Stockwell station.