The London [Images] bomb plot allegedly planned by a cell of doctors failed because a medical syringe used as part of the firing mechanism caused a malfunction, a media report said on Thursday.

Quoting non-classified documents reviewed by it and confirmed by multiple sources, ABC News reported that both cell phone-initiated firing mechanisms, rigged inside a Mercedes E 300 parked several yards from the front door of Tiger Tiger nightclub, had failed.

Fuel-air bombs, whether professionally made or rigged by novices, are notoriously difficult to get to perform as intended, ABC said, adding that is why they are so rarely used.

Despite some surface similarities to vehicle born improvised explosives used in Iraq, these incendiaries were essentially different.

The Iraqi bombs, the report said, are explosives linked to gases either with the idea of increasing their effectiveness or spreading a chemical cloud. The London and Glasgow devices were not explosives at all, but firebombs.

Had the fuel-air bombs successfully ignited into a super-hot fireball filled with roofing nails, casualties would have been almost a certainty among the 500 or so patrons who partied late at the 1,700-person occupancy nightclub that perhaps best symbolises London's vital nightlife scene.