City of London police made 12 arrests over the Christmas period in Manchester and Sunderland in connection with one of Europe's biggest share frauds, in which hundreds of victims lost in excess of £20m.
A 28-year-old man was also arrested in Sweden and is awaiting extradition on charges of money laundering and conspiracy to defraud.
Detectives have been investigating the alleged share fraud since mid-2009, in an investigation code named Operation Soundwave.
One of the companies involved in the investigation is the London-based BFS Corporation which was struck off last November and had never traded.
Marketed as a company specializing in the conversion of algae to biofuel, it duped inexperienced investors with glossy brochures and by issuing impressive looking share certificates.
However, anomalies including phony corporate addresses on the company website and a lack of solid financial data were picked up on by observant investors as early as September 2008.
Detective chief superintendent, Stephen Head, from the City of London Police, told the BBC: "We've been able to seize assets around the world, we've got an international seizure order out, so that we will be able to do our very best to take away the assets from the people profiting from this kind of crime."
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