Operation Symphony police charge staff at scrap metal yards
Twenty people have been accused of 146 offences linked to illegal activity at scrap metal yards in Oxfordshire, Berkshire and Hertfordshire.
Detectives from Operation Symphony have charged staff working at five yards.
The charges relate to the handling of criminal property and possession of firearms.
As well as the 20 people charged, two men have been arrested on suspicion of handling stolen cable, supplying cocaine and cultivating cannabis.
Officers have located three hydroponic cannabis gardens.
Thames Valley Police said a number of people remain on bail and the investigation is on-going.
Operation Symphony is investigating the handling of stolen goods and money laundering, and is part of a police drive to reduce metal theft.
Det Insp Rodger Cartwright said: "The theft of metal has an immense negative impact on communities and businesses and was a particular risk to the country during the Olympic Games."
In January, MPs were concerned metal theft would disrupt travel during London 2012, after thefts from railways led to some train services being cancelled.