Thames Valley Police has charged 20 people with 146 offences linked with illegal activity at scrap metal yards in Oxfordshire, Berkshire and Hertfordshire.
Over the past two weeks, a specialist team of detectives from Operation Symphony have interviewed and charged proprietors and staff linked to five scrap yards.
Operation Symphony is an operation investigating the handling of stolen goods and money laundering. It is part of a force-wide drive to reduce metal theft, which has already resulted in a 45% reduction this year.
In May, the operation executed search warrants at scrap metal yards across Thames Valley and Hertfordshire.
The charges relate to the receipt of criminal property under the Proceeds of Crime Act and the possession of firearms.
On Thursday 6 December the team executed a series of search warrants in the Slough and Langley areas. Two further men have been arrested on suspicion of supplying cocaine, cultivating cannabis and handling large quantities of stolen cable. During the raids police located three hydroponic cannabis gardens.
A number of people remain on bail and the investigation is on-going.
Senior investigating officer Detective Inspector Rodger Cartwright said: "These charges are part of a complex investigation that my team has been conducting for many months. 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.
"Thieves will target a range of metals including lead from roofs and utility power cables, resulting in damage to buildings and businesses as well as causing power cuts."
CLA Regional Director Robin Edwards said: "Be under no apprehension, trading in stolen metal is a very profitable business, netting substantial profits for thieves and handlers and causing others huge economic loss. Thanks to police activity it has become a very risky business for criminals to be in.
"We are pleased that following the CLAs "Scrap the Cash" campaign at the beginning of this year, calling on the Government to ban cash payments to scrap metal sellers, the ban came into force on 3 December."