Muktah Said Ibrahim, the alleged ringleader of the July 21 terrorist “bomb” conspiracy, admitted yesterday that he had made the gang’s explosive devices.

Mr Ibrahim, 29, said that he had built five devices, but, along with the five other men charged, denies conspiring to commit murder or to cause explosions likely to endanger life. The Crown alleges that Mr Ibrahim tried to set off one bomb on a No 26 bus in East London on the Thursday in 2005; three other rucksack devices were partially detonated on Tube trains and the fifth was abandoned in a park.

George Carter Stephenson, QC, Mr Ibrahim’s lawyer, told Woolwich Crown Court: “The position is that all the devices were constructed in the same way, Mr Ibrahim being principally responsible for their construction.”

The court was told that the devices were of a type never seen in Britain by explosives experts. In each case the detonator had gone off but the main charge had failed. The court has been told previously that Mr Ibrahim undertook jihad training in Sudan and returned from a three-month trip to Pakistan in March 2005.

Ian James, the police explosives officer who examined the remains of a device at Oval station in South London, said that he had called in scientists because he was not familiar with the substance it contained.

Claire McGavigan, a scientist at the Forensic Explosives Laboratory, said that she, too, was unfamiliar with it but that tests had revealed the main components to be hydrogen peroxide and polysaccharides, a starchy material found in flour.

Nigel Sweeney, QC, for the prosecution, asked her: “Before the events of July 2005, did the laboratory have any experience of hydrogen peroxide as explosives?”

She replied: “Prior to July 2005 we had never had this sort of material submitted to the laboratory before.”

She said that the material recovered from the scenes was highly volatile.

The remains of the Oval device were stored in protective bags and attempts were made to keep them cool, but they had burnt through three layers of material.

At Shepherd’s Bush station the peroxide mixture was smoking and burning when it was found.

Scientists decided to burn the bulk of the material because it was too unstable to be stored safely. The samples they retained for testing indicated that the explosive was almost as powerful as TNT.

Ms McGavigan said that nails, tacks, washers and screws had been attached to the devices. “They would have quickly propelled away from the explosion, very fast and very hot. Any fragments could embed themselves in a person and cause serious injury. There would be serious damage to the train. There would also be injury and quite possibly death to people in the area.”

The other men accused are Yassin Omar, 26, Manfo Kwaku Asiedu, 33, Ramzi Mohammed, 25, Hussein Osman, 28, and Adel Yahya, 24. The trial continues.

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