SmartDisk is suing BT for negligence, claiming BT forgot to activate an alarm system that it installed – resulting in SmartDisk being the target of a second £500,000 smash-&-grab raid in the space of three months.

SmartDisk managing director Jim Williams said the robberies “bear all the hallmarks of a professional operation”.

He revealed: “The thieves used the same method of robbery on both occasions, cutting wires to disable the building's alarm system. A 7.5 tonne truck was then rammed through premise's doors. The thieves stole half a million pounds of inventory on the first occasion.”

Williams said that after the first robbery he arranged with BT to install a digital alarm to prevent any further wire-cutting incidents.

However, Williams alleges that a BT “oversight” meant that the alarm system remained “uncommissioned”. In the second theft, the thieves stole a further £500,000 of stock. SmartDisk is now suing BT for negligence.

Williams said: "These thieves are professionals. They knew our product line and spent 45 minutes cherry-picking the cream-of-the-crop. They took 500 state-of-the-art FireFly drives and left end-of-line products. They knew what was selling and what wasn't."

Williams added: "The stock has not yet re-surfaced. Police suspect that the goods were stolen-to-order and that the chance of them still being in the UK are slim."

The case is under investigation by Hampshire Constabulary’s Regional Crime Squad.

Williams added: "We’ve been advised by Farnborough police that the thieves may return and have since hired security guards to watch the premises 24 hours a day."

SmartDisk is offering a substantial reward for the capture and recovery of equipment.

Williams, advises consumers to make sure they purchase SmartDisk products from an authorised reseller.