The Financial Services Authority today warned 1,000 people that their names were on a list being used to sell worthless shares.

The watchdog and City of London Police found the personal details on a list being used by criminals involved in so-called boiler room scams.

The FSA has telephoned or written to people whose details appear on the list, the second recovered this year, explaining the steps they can take to protect themselves from boiler room fraud, and telling them what they should do if they think they may already be a victim.

Boiler room scams involve fraudsters using high-pressure sales tactics to con investors into buying non-tradable, overpriced or even non-existent shares. They are thought to cost the UK £200 million a year.

The firms selling the shares are not regulated by the FSA, meaning consumers do not have access to the Financial Ombudsman Service and Financial Services Compensation Scheme if things go wrong.

Jonathan Phelan, head of the unauthorised business department at the FSA, said: “Our sources indicate that the list is a new one and still in use by the fraudsters, so by contacting people on it we hope to cut these boiler rooms off at the pass.”