21/7 bomb claim impossible - expert

A July 21 suspect's claim that he diluted hydrogen peroxide used in the "bombs" with London tap water is "impossible", a court has heard.

Muktar Said Ibrahim admits making all the rucksack devices but claims none of them were capable of detonating. He did not intend to kill or seriously injure anyone and even conducted tests on the peroxide and chapatti flour mixtures to ensure they would only go "pop", Woolwich Crown Court was told earlier.

The jury heard that Ibrahim claims he strengthened the hydrogen peroxide in a north London flat - said to be the home of another alleged bomber, Yassin Omar - but then "watered it down".

Stuart Black, an isotope and geochemistry specialist with 13 years' experience, examined samples of main charge residue found at the four July 21 scenes - Oval, Shepherd's Bush, Warren Street and the Number 26 bus - and from the flat at Curtis House, new Southgate, and the bins outside.

He told the court he also looked at published data on the isotope composition of London tap water, which comes from an underground source.

When asked about Ibrahim's tap water claim, he said it was "impossible" from an isotopic ratio viewpoint.

Ibrahim, 29, of Stoke Newington, north London, is one of six men accused of taking part in an extremist Muslim plot to carry out a series of explosions on the London transport system.

The others are Omar, 26, of New Southgate, north London; Hussain Osman, 28, of no fixed address; Manfo Kwaku Asiedu, 33, of no fixed address; Ramzi Mohammed, 25, of North Kensington, west London; and Adel Yahya, 24, of High Road, Tottenham, north London.

They all deny charges of conspiracy to murder and conspiracy to cause explosions likely to endanger life.