Officers in Scotland and Spain carried out a series of simultaneous raids in March, following a years-long investigation into serious organised crime.
Co-ordinated with the UK's National Crime Agency (NCA), it targeted alleged members of the Lyons - Scotland's dominant crime group - and resulted in 14 arrests across four countries.
Electronic devices, large amounts of cash, company documents, high-end watches and cryptocurrency wallets were said to have been seized as part of the investigation.
A statement in April by the Civil Guard in Spain said the Lyons gang had developed a criminal network in Europe, the Middle East and Asia, using "a complex money laundering network based on shell companies and international financial transactions, managing millions of euros derived from drug trafficking".
It added that the group operated across several countries, including Spain, the United Arab Emirates and Turkey, and is "one of the most significant players in contemporary European organised crime".
It said the Lyons operation involved 18 raids, mostly on the Costa Del Sol and Barcelona.
