National Police have arrested 25 Romanians during an operation carried out in the Valencia Region, Madrid and the Balearic Islands.
The gang, which operated on military lines, used a sophisticated intelligence- gathering system that allowed it to collate information on its targets and the security measures they had either at their homes or businesses.
They then used ultrasonic devices to neutralise guard dogs and an arsenal of tools to force doors and security grills open. The gang also had sophisticated frequency-blocking devices, which it used to disarm alarm systems.
The stolen goods were transported to a central location from where they were sold or sent to Romania.