THE picture of the nail bomb (right) is fuzzy and indistinct but no less chilling for that. It is an X-ray image of the type of nail bomb that Britain’s suicide bombers intended to use. The bomb is packed into a small plastic bottle similar to the kind found in any supermarket.

Inside is an improvised detonator with cable leading out to an electrical device that would provide the charge to set off the bomb. The nails, probably felt-roofing tacks, were attached to the outside of the bottle and encased in layers of clingfilm.

Attaching them to the outside of the bottle is thought to be a quirk of a bombmaker who is now feared to have made dozens of devices.

The bombs were likely to have been “bulked up”, explosives experts say, with cakes of high explosive similar to discs shown in another photograph.

The pictures were leaked to ABC News in America by US law enforcement sources. The items shown were left by the July 7 bombers in a car at Luton railway station.

According to ABC’s report, 16 bombs were found in the boot of a hire car that had been rented by Shehzad Tanweer, 22, who killed himself and six passengers when he set off his bomb on a train near Aldgate station. The American report contradicts information provided by Scotland Yard. They dismissed the idea that a cache of bombs had been found in the Luton car park.

Senior police sources continued to dispute the US reports yesterday, saying that a number of components for bombs were found in the car. The Times has been told that up to 16 of the devices were recovered with nine discs of the TATP-type explosive.

Two cars were examined at the station after the first big breakthrough in the inquiry on July 12. Bomb disposal experts carried out nine explosions on the hire car, a Nissan Micra, before it was taken away.

Scotland Yard is known to be concerned that the images have emerged in the media but the leak is an almost inevitable result of the international cooperation required in such an inquiry. Police and security agencies exchange information daily and some agencies, including the FBI, have agents working full time at Scotland Yard.

There is constant cross-referencing of material to see whether, for example, a type of bomb has been seen before. The result is that information gets less confidential the further it travels. The concern over the pictures in the US is the latest in a series of media management problems to beset the inquiry.

There has been a series of incorrect statements made by the authorities. The July 7 bombs were initially said to have exploded over almost an hour. The timing of the Tube train attacks was later narrowed to a matter of seconds. Incorrect information was also given about the directions in which the trains were travelling.

The July 7 bombers were described as “clean skins” who had not crossed the intelligence radar. But one had been linked to another investigation a year ago and two travelled to Pakistan, where they had contact with al-Qaeda radicals.

The description of the explosive material recovered in Luton and Leeds varied, but sources have admitted that they cannot definitively identify it.

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