Criminal gangs who trick people into investing in fake shares have been targeted by police in the biggest ever international crackdown on fraud.

There are 850 confirmed victims of the gangs in the UK, but police expect the real figure to be in the “multi-thousands.”

The “boiler room fraud” – so-called because of the cramped conditions the gangs worked in – has been the target of a two-year international investigation that resulted in 110 arrests – mostly in the UK and Spain.

Police believe it is the biggest ever operation into this type of fraud.

The operation, code-named Rico, was led by City of London Police and culminated in a series of raids earlier this week.

Commander Steve Head, who is the national economic crime co-ordinator, told the BBC:

 “It is our most important investigation ever, targeting people we believe are at the top of an organised crime network that has been facilitating boiler rooms across Europe and which is suspected of being responsible for millions of pounds of investment fraud.”

Among those under investigation were 10 “tier one criminals” with alleged links to organised crime and drugs, detectives said. Nine of them are British, one is South African.

Eighty-four arrests were made in Spain – where most of the boiler rooms are believed to be based – in raids involving 300 police officers, 40 of them from the UK.

Most of those targeted were seen as ‘vulnerable’ or had a history of share investment and the majority were aged 40 and over.

Police acknowledge that boiler room fraudsters will not disappear and it is important for anyone looking to invest in shares to be vigilant about safety.