More than 100 officers were involved in the operation at seven addresses in London and Hampshire, arresting six men and one woman.
Detectives believe the "highly professional team" behind the British- based conspiracy may have transported more than 100 tonnes of cannabis, as well as cocaine, to countries including Turkey, Canada, Holland, India, Pakistan, Morocco and South Africa. The police say the drugs could have been worth up to pounds 200m at street prices.
Most of the drugs are believed to have been smuggled abroad but a small amount of cannabis, and possibly some cocaine, is understood to have been brought into Britain.
The raids were the result of a 15-month covert operation, codenamed Shadow, organised by the South East Regional Crime Squad.
The squad said it had also asked police in Dublin to make a number of searches on its behalf, and said related inquiries were being carried out in Greece.
Detectives involved in the investigation believe that the conspirators have already laundered at least pounds 3m out of the United Kingdom.
Those arrested in yesterday's simultaneous raids are being questioned at various police stations in Surrey.
Detectives believe that the trafficking network was controlled by highly proficient criminals based in Britain.
In today's raids in London, two men and a women were arrested at a house in Brentford, one man was arrested at a house in Paddington, one man was detained at a house in Pimlico, and another man was arrested in West Hendon. A sixth man was arrested at a house in Basingstoke, Hampshire. No drugs were found.
Detective Chief Inspector Martin Bridger said: "This operation has resulted in the collapse of what we believe to be a very significant organisation who until now had remained undetected. This is a perfect example of the aim of the South East Regional Crime Squad, to proactively pursue criminals of the very highest level, who operate both nationally and internationally, and bring them to justice."
A crime squad spokeswoman added: "We think this was a major international drug-trafficking operation."Reuse content